MPG Calculations

[RichardBedell]

Hi fellow Corvetters. I sold my 1987 with 198,000 miles (all but 9,000) mine so if any one has questions about various high milage issues I will be pleased to try to help.

I now have a Green 2000 Coupe and hope to put as many miles on it. I keep lots of records and notice that the computer shows MPG (average) about 2.5 mpg over the actual MPG. I am relatively sure the number of miles is correct and I certainly know how many gallons I put in the tank. Does anyone know if there is an adjustment that can be made so the computer MPG can be adjusted to match "reality". BTW I regularly average about 39 miles per hour over a tank and then get about 26 MPG although the computer shows 28+. Lastly, you'll all think I'm crazy but I run it on regular with a squirt of Marvel Mystery Oil (8oz per tank every fill or so). I have plenty of power.

 

[justafamilyman]

Hi RichardBedell,
I hope you enjoy your 2000 Vette. I personally like the C5 body style.
As to differences between the "instaneous mpg" and the calculated mpg: I have less than no idea. In fact, just for fun, I had the instaneous mpg in the DIC. I was slowing down at a traffic light and noticed the mpg going -down-. Boy, I would like an explaination on that.

 

[RichardBedell]

Thank's for responding. With all the computer controls it seems logical that there must be a way to fine tune the average MPG calculation. Regarding why the instantanious (SP?) MPG should go down when deaccelerating will be one of those misteries in life. Well I too love the car and and lucky to have it as a daily driver. Be well.

 

[mr_dakota]

mpg

I have noticed on my 97 the the DIC readout for average mpg is about 5% higher than actual. I have also noticed that my mpg is noticably higher than the mpg on the C4 I used to own.

 

[srmrvette]

I agree on your finding that the computer mpg is a bit unreal. On a 1000+ mile trip my '99 6 speed indicated I was getting 29 mpg, but when I added up the gallons and did the math it was a bit over 26. But since I wasn't trying for great mpg I was still WAY pleased at that kind of mpg and all that power.
As for running regular, I did that some with a Camaro Z28 (LT1) just to see what happened. My guess is that the computer just resets things like timing. It runs fine, but you won't get the performance potential that was built into it.

 

[RichardBedell]

MPG

Thanks for your response srmrvette. I know it doesn't reach potential but for a daily driver it is just fine and I can still blow the doors of just about everything else I see on the road except another vette who always gets the right of way by me. BTW in the summer and warm months I found (old 87) that I had to run premium or it would ping. We'll see with this one. I love to follow and watch it go. I sure wish there was a way to fine tune the computer mpg calculations.