Mike -
Here are some specific inspection items that I can recommend. These are pretty much off the top of my head, so don't think of it as a complete list.
1. Quality of paint. Expect rock chips, but look for mismatched panel colors, which may indicate body work.
2. Weatherstripping. C4 W/S is expensive, and is sometimes difficult to install properly. The hatch W/S is intentionally loose at the back, so no need to worry about that. Look for cracks and missing chunks. Even when new, the W/S looks kind of folded and wrinkled, so don't let that throw you.
3. There was an exterior styling change in '91. Some owners of earlier C4's will install the later front and rear pieces if the car sustains damage (or sometimes just because they like that look better). If that's important to you, you'll want to keep it in mind.
4. Power antenna. These have a tendency to not go all the way down. However, the antenna can usually be persuaded to go down with a little help from your hand. Check this out to make sure it goes up w/the radio on, and down w/the radio off.
5. Wheels. Right wheels? Right size tires? There are several combinations, although '89's and up should have standard 17" wheels. How do the tires look? How long since last alignment? How do the wheels look? Curb rash? Oh yeah - ask the owner if he has the wheel locks installed, and if he has the wheel lock.
6. Brake dust. If it's been on a recent drive, there will be some brake dust on the wheels. Is it relatively uniform, or does either side have more build up than another? Speaking of brake dust, does it appear that the owner keeps the wheels clean? Brake dust will eat through the clear coat, and can make the wheels impossible to clean back up.
7. Suspension. Any obvious broken or bent parts? If the car is equipped with Bilstein shocks, it isn't unusual to see oil on the bottom of the shock. It shouldn't be a grease pit, however. If the car has more than 50k miles, you may want to consider replacing the shocks (~$300 for a set of non-FX3 Bilsteins).
8. Exhaust. Stock exhaust, cat-back replacement, or headers? The stock exhaust is the quietest. Many of the aftermarket systems introduce a resonant drone at highway speeds, so you want to note that during your test drive.
9. Engine compartment. Condition of hoses, belts, underhood rubber, and wiring. Early C4's had wiring that will crack/harden over time due to engine compartment temps (I'll have to find the reference for that - I don't have it at my fingertips). How does it look? Does it appear reasonably intact, or does it look like mice sleep in it? Wiring issues are tough gremlins to solve, and you don't want to buy somebody else's wiring nightmare. How about fluid levels and smells? Sniff the AT, PS fluids, and take a gander at the coolant overflow tank.
10. Engine. You'll want this checked out by your pre-purchase inspection. However, you can learn something by removing the oil filler cap and looking closely in the head. Repeat the smell test here. Burned smells or evidence of sludge may be a warning sign.
11. Lights. Do all the lights work? Do the headlamp pods come up together, or do you have C4 lazy eye? Check the interior lights as well (especially the dash lights).
12. Interior. Carpet and seat wear. Driver's side bolsters typically wear out. Later C4's had a rubber coating (I don't remember when it started) on the doors, and console called Dulco or something like that. When it wears, it comes off. There are some references on how to restore it, but I haven't tried any of them. Replacing the Dulco upper console with a reproduction part runs about $150 for the part. Does the A/C work, and does it blow cold air where you expect it to?
13. Radio/CD/Cassette. If you really like listening to your tunes while you drive, then you can plan on replacing the stock stereo with something else. I don't play the radio in mine (the sound of the car is all the music I need), but if you invest in repairs, it will run $150 - $600 (or maybe more if the head unit needs work).
14. Undercarriage. Look for the typical suspects - leaks around seals and such like that. If you have to replace the pinion or transmission rear seal, you'll have to remove the exhaust system to get to it. Of course, if you do that, then you can add C-Beam strengtheners from ZFDoc.
15. Targa top. If you have a blue or bronze clear top, be sure to look for cracks and/or crazing. Crazing will occur if the car has been stored outside, as the plastic reacts to UV radiation (do a google search on crazing). Crazing looks crappy, but doesn't affect the strength of the top. Cracks, on the other hand, may be cause to replace the top (depends - some people have repaired their cracks, and it never gets bigger - but it still looks like crap). A replacement top from a quality source will run about $700+.
I'm assuming you plan to spend some money for a pre-purchase inspection of the potential car. Find someone that has a C4 that you trust to go with you.
Look at lots of cars - I spent a year looking for mine, and learned a lot of the things I mentioned along the way.
IMHO, if you find the right C4 - a well maintained, solid example that has the equipment you're looking for - then it may be well worth the investment. I'm not saying that this particular car is worth $12k, but if you find the car you want, in the right color and options, then you might consider paying a premium for it.
I spent about a year looking for my Vette. Take your time and enjoy the search.
Good Luck!
Steven
