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C5 vs. C6 comparison--Coupes and Z06s

Gersh

Well-known member
Joined
Apr 1, 2005
Messages
218
Location
Kentucky
Corvette
"06 Z06, Kawasaki ZZR, "66 supercharged Chev 489
C5 Z06 and Coupe vs. C6 Z06 and Coupe
(Picture links at end)


INTRODUCTION

By way of introduction and explanation, let me give a little history.
Terri and I have been married for 20 years, and we had a 1968 convertible Vette with 4 speed and 327 about 17 years ago. We sold it before we moved from Oregon to Kentucky, 15 years ago. When we settled down a bit more and had kids, we gave up ideas about Corvettes, twin-turbo Stealth, and the like—temporarily.

About 2000, I had a Crown Victoria that I put a Vortech supercharger in, but it was never really satisfying—too much compromise between sport and family car. (Obviously).
In 2002, I started looking for a late model used Z06, with the 405 HP motor, and found a car in Florida with only 800 miles on it. By chance Terri was in Florida that week, so I called and asked her if she wanted to drive home instead of flying. It all worked out well, and I soon realized I liked the car so much I wanted her to have one too. We found a used 2001 Coupe in Magnetic Red, and this time I went to Detroit and drove it home.
My car was driven daily, and she used hers whenever she didn’t have to carry kids around, so we both got a lot of use out of them for nearly four years.

In 2005, I started getting excited about the new Z06 because of the LS7 engine. I was not willing to pay more than MSRP—I’m too cheap--so I was in contact with Kerbeck salesmen for the last half of the year. We were intending to get Terri a new Corvette as well, so finally I decided to go ahead and order Terri a new car from Kerbeck to increase my chances of getting on the Z06 list, and it worked! As a new (therefore previous and preferred) customer, and some incredibly lucky timing I was able to order my car very shortly after, and it was built soon after hers. Terri ordered a Coupe in Monterey Red with most of the options, and I ordered a Z06 in Daytona Sunset Orange Metallic with polished wheels and no other (weight-adding) options. We took delivery about a month ago, and for a few weeks we had all four cars for comparison. Last week we sold her C5, but I am holding on to my old Z06 (the “Black Panther”) for the time being. (Regrettably, I heard recently that Kerbeck’s has now started asking a premium over MSRP for their C6 Z06 sales).

This then is one man’s attempt to compare the four cars. I’m not a race car driver or engineer, just an enthusiastic consumer with an analytical bent. None of the four has significant mods—just CAGS eliminators and a few decorative additions. If I step on anyone’s toes, I’m sorry, and keep in mind, these are only my perspective.



BODY, INTERIOR, FIT AND FINISH

Terri’s new car is Monterey Red and mine is DSOM. We both like the old Magnetic Red, and we both like the Monterey Red even better! We both chose Black/Black interiors, which is not typical—I hear our car colors are generally being ordered with Cashmere interiors. Personally, I could do without the metallic accents around the interior, but there is no choice about that, apparently. The C5 cars didn’t have those accents, and I like the old look better—the accents seem a little cheesy. It took me a while to get used to the Orange, but by now I think it was a great choice. The body style also took me a while to get used to. I always liked the distinctive “hard-top” of the C5 Z06, and I thought I would really miss that, but by now I find the new Z06 more striking and overall more attractive. The C6 cars have sharper angles and a more aggressive look, compared to C5s (especially the front end and front fenders). When put side by side the C5s look a bit too smooth and rounded--less distinctive with less “personality”. (Remember, it’s only one guy’s viewpoint.) The difference is especially dramatic with the C6 Z06, which has a taller rear spoiler, flared fenders, rear brake cooling ducts, hood scoop, and black fender guards. But with that said, I love my C5 Z06, performance and appearance.

All these cars have beautiful workmanship. I have repeatedly read Corvette reviews saying that a high-end sports-car should have a fancier interior. Personally I have no experience with Mercedes, Porsche, Lexus, and the like, so maybe I’m just ignorant of real luxury, but I have no problem with the degree of luxury in my Vettes. Should they have velvet dashboard covers and gold inlaid instrument panels???
Due to my long arms, I find the center console to be too high for ideal comfort. The shifter has a little shorter throw on the C6, but like the C5, it is still set too high for my arm length—it lines up well with the center console, which is about two inches too high.

The interior sound levels are fairly comparable in the C5 Coupe vs. C6 Coupe—both pretty quiet. The C5 Z06 is louder than the C6 Z06, unless you disable the exhaust valves, which I did. Then the C6 is a little louder and harsher sounding, especially at lower RPMs. With the exhaust valves open, there is some annoying resonation at certain RPMs. (Terri tells me the resonance is not noticeable in the passenger seat, just the driver seat.) The C5 Z06 has a troublesome console door, and the new cars seem to have fixed that with better hinges on the console doors. The C6 has thumb buttons for opening the doors from the inside, which I like, but might be bad for people with severe arthritis in their thumbs (like my Mom). I love the race car pedals, which they kept on the new cars too.

The C6 wheels are nice. They look good and the smooth surfaces wipe clean easily (same with the C5 wheels). But the Z06 wheels are not as easy to get into for cleaning as the Coupe—the price of looking distinctive, I guess. Interestingly, the C6 Coupe wheel spokes are a little wider than the C5 Coupe spokes—tougher looking I think, whereas the C6 Z06 spokes went the opposite direction. They are slimmer than the C5 Z06 spokes—more elegant looking. Overall, I like the new wheels better on both cars.
I’ve been driving my new Z06 to auto parts stores, getting stuff I need to restore an old Charger I’m working on. Lots of car-oriented people at parts stores, and the C6 Z06 gets a bunch of attention—I haven’t heard any bad comments about its looks.



DRIVING—OH, YEAH!

One drive I haven’t done on the new car yet is the High Speed Test. A few years ago, I drove the C5 up to 162 MPH. In order to assure as much safety as possible, we picked a Sunday morning with good weather, drove to a straight stretch of Interstate 24, me in the C5 Z06 and Terri in the family car with my son. We had two-way radios, good for clear communication for a mile or so. I pulled off to the side and Terri drove half a mile further, then pulled off. We waited till there was a long empty space in traffic, then when more traffic started coming up behind me, I told Terri to go, and we both accelerated to 70 MPH. She was ahead looking for traffic, road problems, police, etc, and called all clear, so I put the radio down (leaving it on so she could talk to me) and put it in 3rd and floored it. (I left the traffic behind, and there was no traffic for more than half a mile ahead.) Then 4th and then 5th gear. Wow! My goal was 150 MPH, but the car was so strong I got there in no time. At 162, the car was still accelerating strongly, but the expansion joints on the bridge over the Ohio River made me nervous, so I called it good… I was back to safer speeds even before I caught up with Terri. The car is VERY quick. My goal for the C6 Z06 is 180 MPH, but don’t tell anyone. Anyway, it will be a better location—no bridges.

The new keyless entry and push button start is nice. I never had an OLD car with that feature, but I guess it was standard before keys. I modified my routine a bit and adapted to the keyless thing just fine. The C6 cars have several options for whether you want the car to lock automatically when you leave the car, whether you want to be reminded to lock (three obnoxious little horn beeps—I turned that off right away) and which doors to unlock automatically when you come near, as well as whether you want to be reminded if you leave the Fob in the car. Interestingly, the car knows whether the Fob is actually inside vs. just outside the car.
Terri’s car has built-in universal home remote, which is nice—no extra remotes hanging off the visors. I would have liked to get that option, but it would have required a whole package including side airbags, telescoping wheel, etc, etc.

Terri likes her C6 Coupe much better than the C5 Coupe. She appreciates the light steering effort, and improved throttle response. Her new transmission feels maybe just a little cleaner shifting than the C5. The Tremec transmission in the new Z06 feels a bit stiffer than the C5 Z06, but maybe because it is new, and will loosen up a bit with use. Brakes in all four cars seem superb--never a problem in any of the cars, (except for getting the wheels dirty in a hurry.)

Both our C5 cars had steering wheel unlocking failures, for which the factory does not accept responsibility (Terri’s cost over $400 to get repaired). Fortunately, the C6s have no steering wheel locks. Incidentally, I think C5 owners should consider buying an aftermarket unit to disable the steering lock--about $50 and easy to install. But DON’T get the factory recall done on the steering lock, because that doesn’t even prevent it from locking up, and I heard it will make the aftermarket unit unusable.

The hand-built LS7 engine in the new Z06 has quite a bit more mechanical engine noise than the LS6 engine—maybe valves or lifters? The C5 Z06 always had a tendency to a little popping (backfire) between gears—when the clutch is in and gas is off—especially when cold, and mostly in lower gears, maybe because I was using a little higher RPM. The C6 cars have a different response to letting off the throttle. They don’t reduce RPM rapidly when I take my foot off the throttle; the RPMs go down much more gradually, as if the computer is trying to keep things smooth and stable.

The cars all have a low underbody spoiler to reduce drag and turbulence at speed. The C6 Z06 also has an extra air dam along the lower edge of the front bumper. I have been happy to find that the new Z06 is less likely than the old Z06 to rub on driveways. I also read that the C6 was designed to be less noisy when it rubs, so maybe that is what I am experiencing, but some driveways where my C5 always rubbed, the C6 doesn’t seem to at all.

The C5 Coupe was fuel-rated at 18/28 mpg, and the C5 Z06 at 17/27 (like the C6 Coupe). The new Z06 is rated 16/26, but so far, I think it is worse than that—I notice a big difference in fuel consumption, though maybe I’m driving it a bit more enthusiastically than normal…

Out of all the hundreds of times I drove my C5 Z06, I only road raced a few times (Mustang GT, big BMW, Firebird, Harley-Davidson, Camaro, and once a small pick-up to entertain us both. A Ferrari driver recently pretended I didn’t exist—maybe he didn’t want to get his ass kicked.) So the daily drive is the most important thing, and I find that daily driving is a joy. That means that the primary value of the car (along with getting to and from work, hardware store, Gary’s house, etc) is dependent on how it feels to drive, not necessarily whether it is faster than the car in the next lane. The C5 Z06 has transmission ratios which gives it more low-end boost, as compared to the Coupe. I will show this in more detail in the next section, but for driving impressions it means that the car feels much more powerful, and therefore more fun to drive… And that is what it is all about. On the other hand, the low gearing (in the C5 Z06), makes 1st gear seems a little too short, so lots of times I would just take off in 2nd gear. The C6 Z06 has taller gearing, more like both Coupes. But it also has 25% more horsepower, so it handles the taller gearing with authority. Both Z06s will spin the tires in 2nd gear (just with hard acceleration, not by dropping the clutch). But for everyday driving, the C6 Z06 has a more relaxed, comfortable use of the lower gears, without having to shift so soon.



GEAR RATIOS AND POWER

Speeds in MPH at 3000 RPM (all with manual 6 speed transmissions):

C5 Coupe C5 Zo6 C6 Coupe C6 Z06

1st Gear 26 21 26 26
2nd Gear 38 31 38 37
3rd Gear 53 46 52 52
4th Gear 69 67 68 69
5th Gear 93 80 92 92
6th Gear 140 118 131 136


I arbitrarily picked 3000 RPM for gear ratio comparison. Since the cars have different redlines, these won’t directly translate to speeds at redline. Note that these are attempted measured speeds, trying to read the speedometer and tachometer at the same time, and may be off by a couple miles an hour, especially in the higher gears. (The 6th gear speeds were tested at 1500 RPM then multiplied by two for speed at 3000 RPM). They could also be affected by tire pressure or tire wear, but all cars had fairly new stock tires on at time of testing.

(Please note that throughout this article, when I use the term “shorter gearing” I am indicating a lower speed at a given RPM, so it is the opposite of the rear axle numbers, where a higher number means lower speed at a given RPM). The remarkable similarity of the C5 Coupe with both C6 cars in 1st through 5th gears suggests they may actually have the same gear ratios, but I couldn’t measure them precisely enough to be sure. The C5 Z06 stands out for its shorter gearing—15 to 23% shorter, except for 4th gear, which seems to be an anomaly. I double-checked it and the 67 MPH is correct… Possibly this was put in to maintain the fuel-efficiency benefits of the CAGS, but then it makes the 1st to 4th jump awfully long. (One of the first things I did when I got the car was to put on a skip-shift eliminator, and my new car will be getting one soon.)

I have come to the conclusion that the shorter gearing is one of the biggest differences between the C5 Coupe and Z06. Terri’s C5 Coupe always felt underpowered, though the actual horsepower difference is not that great. Now, comparing her 400 HP C6 Coupe with the 405 HP C5 Z06, the Z06 drives as if it is much stronger—and I am pretty sure the gearing is the main reason. Her new Coupe doesn’t want to spin the tires in 2nd gear under hard acceleration, whereas the Z06 will ALWAYS spin the tires in 2nd gear or activate the traction control. That makes a big difference in how strong the car feels.



ANALYSIS AND SUMMARY

I drove the C5 Z06 daily for four years, and have long said 3rd gear is my favorite. It can use all its power in third, generally maintaining traction (unless the road is damp or it is on a little curve or hill), but feels like it is almost ready to spin the tires, with phenomenal acceleration and a superb exhaust roar. The C6 Z06 does not sound quite as good at full throttle as the C5 Z06. It does have more power, as advertised, and uses a lot of that extra thrust compensating for the higher gearing. It seems like there are fewer opportunities to “open it up” than with the C5.

I don’t know that much about the Z51 packages, but it is my understanding that the C5 Coupe with Z51 has lower gearing than the standard Coupe (like the Z06). I think it must be a blast as well. I have also seen published figures indicating that the C6 Coupe with Z51 has lower gearing as well, and this would make it a great choice, probably as much fun to drive as a C5 Z06

If I ask Terri which car she prefers, she says C6 Coupe (over C6 Z06 because of the color and removable top), followed by the C5 Coupe (again color and removable top), then the C6 Z06, with the C5 Z06 coming in last. I disagree strongly. For me, the C6 Z06 comes in first, for power and surprisingly to me, also for its new body lines. But the C5 Z06 is easily in 2nd place, for sheer fun driving. As far as value for the money, it entirely depends on each buyer’s financial situation, so it’s hard to address the issue. But if I were offered a free car, either a brand new C6 Coupe or my old C5 Z06, with the stipulation that I was going to keep it and drive it, not sell it, I would take the old Z06. Due to the gear ratios, it feels so much stronger than the C6 Coupe, let alone the C5 Coupe that they just can’t compete. Oh, wait! Maybe I would take the new C6 Coupe and put a different gear in the rear axle to rev up the RPMs and boost the sensation of power…

Submitted by Gersh Lundberg

PICTURES
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Joined
Oct 25, 2002
Messages
2,634
Location
Lilburn GA
Corvette
2002 Yellow Z06 (sold); 1999 Pewter FRC (sold)
Gersh,
Fantastic comparison, and the photos are terrific also.
With the 4 Vettes in the family- 2 of them Z06's, you are a lucky man.

Tammy
 

Gorgon

Well-known member
Joined
Jul 15, 2002
Messages
1,040
Location
Philadelphia, PA
Corvette
None
Nice write up Gersh. Enjoyed it quite a bit.

One note, the C5 Z51 package was a suspension package only. The Z51 package on the C6 coupe also offered different brakes, a transmission cooler and a differently geared manual trasmission. The ratios for the C6 Z51 coupe are identical to the C5 Z06 ratios and would likely make the car feel more on par with the C5 Z06 that you have.

Leon
 

soggytaco

Well-known member
Joined
Oct 22, 2005
Messages
115
Location
Southern NH
Corvette
96 CE LT4
Gersch,

That was an awsome write up thank you. You are a lucky man to have so many great cars.
 

Gersh

Well-known member
Joined
Apr 1, 2005
Messages
218
Location
Kentucky
Corvette
"06 Z06, Kawasaki ZZR, "66 supercharged Chev 489
Gorgon said:
Nice write up Gersh. Enjoyed it quite a bit.

One note, the C5 Z51 package was a suspension package only. The Z51 package on the C6 coupe also offered different brakes, a transmission cooler and a differently geared manual trasmission. The ratios for the C6 Z51 coupe are identical to the C5 Z06 ratios and would likely make the car feel more on par with the C5 Z06 that you have.

Leon

Leon--
Thanks for the input; I was wondering about that issue. I suspect that the C6 Coupe with that package would make a great choice for someone like me, who loves that sensation of extra, unneeded power.
Gersh
 
N

Nomad 69

Guest
Gersh,

I'm a new owner of a ZO6. Great write up and I've learned a lot. I also heard about making my ZO6 a little louder by taking out a fuse. Do you know anything about this...does/will it have long term issues? Thanks

Damon
 

Pseudomind

Well-known member
Joined
Mar 9, 2005
Messages
668
Location
Jacksonville, FL
Corvette
2002 MY Roadster
Removing a fuse?

I would image it would have something to do with the exhaust butterfly valves and keeping them open at low speeds.

Building the Beast
A look inside the Corvette Z06.

By Dave Kimble
October 2005


Electronics also plays a part in the exhaust system, allowing full-throttle backpressure to be kept to a minimum while still safely passing the drive-by noise test. The stainless-steel pipes' diameter has increased from 2 1/2 to 3 in. and they are welded to a pair of larger-volume mufflers. These mufflers each have the familiar pair of exhaust tips but the inboard ones are normally closed by vacuum-operated butterfly valves. They are allowed to open only when their electronic control system senses the throttle-plate angle and engine rpm have reached a predetermined point that is well beyond the range of normal driving.


Building the Beast
 

JJS

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Joined
Feb 19, 2003
Messages
1,315
Location
Oregon
Corvette
2013 Triple Black GS, Previous cars: 1971 LT-1
Great write up, Gersh. I normally just read the responses to long posts such as yours, but I found your article to be very entertaining an highly informative.
-John
 

billyz06-2003

Well-known member
Joined
Apr 30, 2006
Messages
484
Location
stl. louis mo.
Corvette
2009 callaway crystal red coupe, 1995 pace car
Really a great artical, as a zo6 owner i know what you speak of. hoping to have magna sc on next spring which with 7 lb. boost will yeal about 500rwhp, which should get my attention.:):):):):):):):):):):):):):)Billy
 

Gersh

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Joined
Apr 1, 2005
Messages
218
Location
Kentucky
Corvette
"06 Z06, Kawasaki ZZR, "66 supercharged Chev 489
Billy--
Thanks for the kind words. I wrote this about a year and a half ago, and am surprised you came across it. Maybe it should be in the C5 discussion instead of C6...
Gersh
 
Joined
Jun 22, 2007
Messages
153
Location
marysville,wa
Corvette
08 Atomic orange, Z-51, 6 speed
[Great informative and very imppressing statistics. That must have been a on-going project for quite some time. Awesome photos quote=Gersh;679268]C5 Z06 and Coupe vs. C6 Z06 and Coupe
(Picture links at end)


INTRODUCTION

By way of introduction and explanation, let me give a little history.
Terri and I have been married for 20 years, and we had a 1968 convertible Vette with 4 speed and 327 about 17 years ago. We sold it before we moved from Oregon to Kentucky, 15 years ago. When we settled down a bit more and had kids, we gave up ideas about Corvettes, twin-turbo Stealth, and the like—temporarily.

About 2000, I had a Crown Victoria that I put a Vortech supercharger in, but it was never really satisfying—too much compromise between sport and family car. (Obviously).
In 2002, I started looking for a late model used Z06, with the 405 HP motor, and found a car in Florida with only 800 miles on it. By chance Terri was in Florida that week, so I called and asked her if she wanted to drive home instead of flying. It all worked out well, and I soon realized I liked the car so much I wanted her to have one too. We found a used 2001 Coupe in Magnetic Red, and this time I went to Detroit and drove it home.
My car was driven daily, and she used hers whenever she didn’t have to carry kids around, so we both got a lot of use out of them for nearly four years.

In 2005, I started getting excited about the new Z06 because of the LS7 engine. I was not willing to pay more than MSRP—I’m too cheap--so I was in contact with Kerbeck salesmen for the last half of the year. We were intending to get Terri a new Corvette as well, so finally I decided to go ahead and order Terri a new car from Kerbeck to increase my chances of getting on the Z06 list, and it worked! As a new (therefore previous and preferred) customer, and some incredibly lucky timing I was able to order my car very shortly after, and it was built soon after hers. Terri ordered a Coupe in Monterey Red with most of the options, and I ordered a Z06 in Daytona Sunset Orange Metallic with polished wheels and no other (weight-adding) options. We took delivery about a month ago, and for a few weeks we had all four cars for comparison. Last week we sold her C5, but I am holding on to my old Z06 (the “Black Panther”) for the time being. (Regrettably, I heard recently that Kerbeck’s has now started asking a premium over MSRP for their C6 Z06 sales).

This then is one man’s attempt to compare the four cars. I’m not a race car driver or engineer, just an enthusiastic consumer with an analytical bent. None of the four has significant mods—just CAGS eliminators and a few decorative additions. If I step on anyone’s toes, I’m sorry, and keep in mind, these are only my perspective.



BODY, INTERIOR, FIT AND FINISH

Terri’s new car is Monterey Red and mine is DSOM. We both like the old Magnetic Red, and we both like the Monterey Red even better! We both chose Black/Black interiors, which is not typical—I hear our car colors are generally being ordered with Cashmere interiors. Personally, I could do without the metallic accents around the interior, but there is no choice about that, apparently. The C5 cars didn’t have those accents, and I like the old look better—the accents seem a little cheesy. It took me a while to get used to the Orange, but by now I think it was a great choice. The body style also took me a while to get used to. I always liked the distinctive “hard-top” of the C5 Z06, and I thought I would really miss that, but by now I find the new Z06 more striking and overall more attractive. The C6 cars have sharper angles and a more aggressive look, compared to C5s (especially the front end and front fenders). When put side by side the C5s look a bit too smooth and rounded--less distinctive with less “personality”. (Remember, it’s only one guy’s viewpoint.) The difference is especially dramatic with the C6 Z06, which has a taller rear spoiler, flared fenders, rear brake cooling ducts, hood scoop, and black fender guards. But with that said, I love my C5 Z06, performance and appearance.

All these cars have beautiful workmanship. I have repeatedly read Corvette reviews saying that a high-end sports-car should have a fancier interior. Personally I have no experience with Mercedes, Porsche, Lexus, and the like, so maybe I’m just ignorant of real luxury, but I have no problem with the degree of luxury in my Vettes. Should they have velvet dashboard covers and gold inlaid instrument panels???
Due to my long arms, I find the center console to be too high for ideal comfort. The shifter has a little shorter throw on the C6, but like the C5, it is still set too high for my arm length—it lines up well with the center console, which is about two inches too high.

The interior sound levels are fairly comparable in the C5 Coupe vs. C6 Coupe—both pretty quiet. The C5 Z06 is louder than the C6 Z06, unless you disable the exhaust valves, which I did. Then the C6 is a little louder and harsher sounding, especially at lower RPMs. With the exhaust valves open, there is some annoying resonation at certain RPMs. (Terri tells me the resonance is not noticeable in the passenger seat, just the driver seat.) The C5 Z06 has a troublesome console door, and the new cars seem to have fixed that with better hinges on the console doors. The C6 has thumb buttons for opening the doors from the inside, which I like, but might be bad for people with severe arthritis in their thumbs (like my Mom). I love the race car pedals, which they kept on the new cars too.

The C6 wheels are nice. They look good and the smooth surfaces wipe clean easily (same with the C5 wheels). But the Z06 wheels are not as easy to get into for cleaning as the Coupe—the price of looking distinctive, I guess. Interestingly, the C6 Coupe wheel spokes are a little wider than the C5 Coupe spokes—tougher looking I think, whereas the C6 Z06 spokes went the opposite direction. They are slimmer than the C5 Z06 spokes—more elegant looking. Overall, I like the new wheels better on both cars.
I’ve been driving my new Z06 to auto parts stores, getting stuff I need to restore an old Charger I’m working on. Lots of car-oriented people at parts stores, and the C6 Z06 gets a bunch of attention—I haven’t heard any bad comments about its looks.



DRIVING—OH, YEAH!

One drive I haven’t done on the new car yet is the High Speed Test. A few years ago, I drove the C5 up to 162 MPH. In order to assure as much safety as possible, we picked a Sunday morning with good weather, drove to a straight stretch of Interstate 24, me in the C5 Z06 and Terri in the family car with my son. We had two-way radios, good for clear communication for a mile or so. I pulled off to the side and Terri drove half a mile further, then pulled off. We waited till there was a long empty space in traffic, then when more traffic started coming up behind me, I told Terri to go, and we both accelerated to 70 MPH. She was ahead looking for traffic, road problems, police, etc, and called all clear, so I put the radio down (leaving it on so she could talk to me) and put it in 3rd and floored it. (I left the traffic behind, and there was no traffic for more than half a mile ahead.) Then 4th and then 5th gear. Wow! My goal was 150 MPH, but the car was so strong I got there in no time. At 162, the car was still accelerating strongly, but the expansion joints on the bridge over the Ohio River made me nervous, so I called it good… I was back to safer speeds even before I caught up with Terri. The car is VERY quick. My goal for the C6 Z06 is 180 MPH, but don’t tell anyone. Anyway, it will be a better location—no bridges.

The new keyless entry and push button start is nice. I never had an OLD car with that feature, but I guess it was standard before keys. I modified my routine a bit and adapted to the keyless thing just fine. The C6 cars have several options for whether you want the car to lock automatically when you leave the car, whether you want to be reminded to lock (three obnoxious little horn beeps—I turned that off right away) and which doors to unlock automatically when you come near, as well as whether you want to be reminded if you leave the Fob in the car. Interestingly, the car knows whether the Fob is actually inside vs. just outside the car.
Terri’s car has built-in universal home remote, which is nice—no extra remotes hanging off the visors. I would have liked to get that option, but it would have required a whole package including side airbags, telescoping wheel, etc, etc.

Terri likes her C6 Coupe much better than the C5 Coupe. She appreciates the light steering effort, and improved throttle response. Her new transmission feels maybe just a little cleaner shifting than the C5. The Tremec transmission in the new Z06 feels a bit stiffer than the C5 Z06, but maybe because it is new, and will loosen up a bit with use. Brakes in all four cars seem superb--never a problem in any of the cars, (except for getting the wheels dirty in a hurry.)

Both our C5 cars had steering wheel unlocking failures, for which the factory does not accept responsibility (Terri’s cost over $400 to get repaired). Fortunately, the C6s have no steering wheel locks. Incidentally, I think C5 owners should consider buying an aftermarket unit to disable the steering lock--about $50 and easy to install. But DON’T get the factory recall done on the steering lock, because that doesn’t even prevent it from locking up, and I heard it will make the aftermarket unit unusable.

The hand-built LS7 engine in the new Z06 has quite a bit more mechanical engine noise than the LS6 engine—maybe valves or lifters? The C5 Z06 always had a tendency to a little popping (backfire) between gears—when the clutch is in and gas is off—especially when cold, and mostly in lower gears, maybe because I was using a little higher RPM. The C6 cars have a different response to letting off the throttle. They don’t reduce RPM rapidly when I take my foot off the throttle; the RPMs go down much more gradually, as if the computer is trying to keep things smooth and stable.

The cars all have a low underbody spoiler to reduce drag and turbulence at speed. The C6 Z06 also has an extra air dam along the lower edge of the front bumper. I have been happy to find that the new Z06 is less likely than the old Z06 to rub on driveways. I also read that the C6 was designed to be less noisy when it rubs, so maybe that is what I am experiencing, but some driveways where my C5 always rubbed, the C6 doesn’t seem to at all.

The C5 Coupe was fuel-rated at 18/28 mpg, and the C5 Z06 at 17/27 (like the C6 Coupe). The new Z06 is rated 16/26, but so far, I think it is worse than that—I notice a big difference in fuel consumption, though maybe I’m driving it a bit more enthusiastically than normal…

Out of all the hundreds of times I drove my C5 Z06, I only road raced a few times (Mustang GT, big BMW, Firebird, Harley-Davidson, Camaro, and once a small pick-up to entertain us both. A Ferrari driver recently pretended I didn’t exist—maybe he didn’t want to get his ass kicked.) So the daily drive is the most important thing, and I find that daily driving is a joy. That means that the primary value of the car (along with getting to and from work, hardware store, Gary’s house, etc) is dependent on how it feels to drive, not necessarily whether it is faster than the car in the next lane. The C5 Z06 has transmission ratios which gives it more low-end boost, as compared to the Coupe. I will show this in more detail in the next section, but for driving impressions it means that the car feels much more powerful, and therefore more fun to drive… And that is what it is all about. On the other hand, the low gearing (in the C5 Z06), makes 1st gear seems a little too short, so lots of times I would just take off in 2nd gear. The C6 Z06 has taller gearing, more like both Coupes. But it also has 25% more horsepower, so it handles the taller gearing with authority. Both Z06s will spin the tires in 2nd gear (just with hard acceleration, not by dropping the clutch). But for everyday driving, the C6 Z06 has a more relaxed, comfortable use of the lower gears, without having to shift so soon.



GEAR RATIOS AND POWER

Speeds in MPH at 3000 RPM (all with manual 6 speed transmissions):

C5 Coupe C5 Zo6 C6 Coupe C6 Z06

1st Gear 26 21 26 26
2nd Gear 38 31 38 37
3rd Gear 53 46 52 52
4th Gear 69 67 68 69
5th Gear 93 80 92 92
6th Gear 140 118 131 136


I arbitrarily picked 3000 RPM for gear ratio comparison. Since the cars have different redlines, these won’t directly translate to speeds at redline. Note that these are attempted measured speeds, trying to read the speedometer and tachometer at the same time, and may be off by a couple miles an hour, especially in the higher gears. (The 6th gear speeds were tested at 1500 RPM then multiplied by two for speed at 3000 RPM). They could also be affected by tire pressure or tire wear, but all cars had fairly new stock tires on at time of testing.

(Please note that throughout this article, when I use the term “shorter gearing” I am indicating a lower speed at a given RPM, so it is the opposite of the rear axle numbers, where a higher number means lower speed at a given RPM). The remarkable similarity of the C5 Coupe with both C6 cars in 1st through 5th gears suggests they may actually have the same gear ratios, but I couldn’t measure them precisely enough to be sure. The C5 Z06 stands out for its shorter gearing—15 to 23% shorter, except for 4th gear, which seems to be an anomaly. I double-checked it and the 67 MPH is correct… Possibly this was put in to maintain the fuel-efficiency benefits of the CAGS, but then it makes the 1st to 4th jump awfully long. (One of the first things I did when I got the car was to put on a skip-shift eliminator, and my new car will be getting one soon.)

I have come to the conclusion that the shorter gearing is one of the biggest differences between the C5 Coupe and Z06. Terri’s C5 Coupe always felt underpowered, though the actual horsepower difference is not that great. Now, comparing her 400 HP C6 Coupe with the 405 HP C5 Z06, the Z06 drives as if it is much stronger—and I am pretty sure the gearing is the main reason. Her new Coupe doesn’t want to spin the tires in 2nd gear under hard acceleration, whereas the Z06 will ALWAYS spin the tires in 2nd gear or activate the traction control. That makes a big difference in how strong the car feels.



ANALYSIS AND SUMMARY

I drove the C5 Z06 daily for four years, and have long said 3rd gear is my favorite. It can use all its power in third, generally maintaining traction (unless the road is damp or it is on a little curve or hill), but feels like it is almost ready to spin the tires, with phenomenal acceleration and a superb exhaust roar. The C6 Z06 does not sound quite as good at full throttle as the C5 Z06. It does have more power, as advertised, and uses a lot of that extra thrust compensating for the higher gearing. It seems like there are fewer opportunities to “open it up” than with the C5.

I don’t know that much about the Z51 packages, but it is my understanding that the C5 Coupe with Z51 has lower gearing than the standard Coupe (like the Z06). I think it must be a blast as well. I have also seen published figures indicating that the C6 Coupe with Z51 has lower gearing as well, and this would make it a great choice, probably as much fun to drive as a C5 Z06

If I ask Terri which car she prefers, she says C6 Coupe (over C6 Z06 because of the color and removable top), followed by the C5 Coupe (again color and removable top), then the C6 Z06, with the C5 Z06 coming in last. I disagree strongly. For me, the C6 Z06 comes in first, for power and surprisingly to me, also for its new body lines. But the C5 Z06 is easily in 2nd place, for sheer fun driving. As far as value for the money, it entirely depends on each buyer’s financial situation, so it’s hard to address the issue. But if I were offered a free car, either a brand new C6 Coupe or my old C5 Z06, with the stipulation that I was going to keep it and drive it, not sell it, I would take the old Z06. Due to the gear ratios, it feels so much stronger than the C6 Coupe, let alone the C5 Coupe that they just can’t compete. Oh, wait! Maybe I would take the new C6 Coupe and put a different gear in the rear axle to rev up the RPMs and boost the sensation of power…

Submitted by Gersh Lundberg

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S

Saber 6

Guest
Mid America has a remote switch that allows the butterfly values to be open at low speeds. Cost is around $100.
 
Joined
Jun 22, 2007
Messages
153
Location
marysville,wa
Corvette
08 Atomic orange, Z-51, 6 speed
It is too bad you could not have driven a C6 coupe with the Z-51 package.. Gearing and handling are superb.
 

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