Hey Rob,
I used to own a 90 C4 before I purchased my NSX. It is a very nice AWD car. It was computer controlled AWD system... technology taken from the 959, although I understand that the viscous coupling of the 993 AWD system was lighter and more responsive.
I did the maintenance myself, although I still can't get used to adding 13 quarts of oil everytime I oil changed it. The car leaked a little oil, but this is supposed to be typical of these 964's and 993's.
I loved the automatic spoiler that pops up at 45mph and descends at 7mph, although the newer ones that operate at 75mph makes more sense. I had the optional turbo seats, so there were great side bolsters. No problems with my lats hitting on corners.
The shifter was the first of the modern 911s that actually didn't resemble a school bus shifter with it coming straight from the floorboard.
The climate controls were still a bit counter-intuitive, and the vents were an improvement over the older 911s but still not nearly as good as the NSX. The first thing I did was to replace the ugly 7-spoke wheels for the newer 993 5-spoke wheels.
I had a problem with the dual mass flywheel and clutch, so that was a large bill of approximately $5000. My turning light wand broke, the window switch was finiky, the Blaupunkt headunit was not very good (too many small buttons that all looked and felt the same), the two rear seats were practically non-functional, and the headlights were not as bright as you would expect, considering how huge those lamphousings are.
I owned it for about 3 or 4 years, and have fond memories of the car, but the NSX is a much better car in so many ways.
I hope this helps,
J.
