The one in the picture above was my favorite of all time. It had functional rack and pinion steering, a three speed manual transmission, coil-over suspension, and a horizontally opposed four-cylinder engine. (you could SEE IT ALL WORK!) I can’t tell you how cool this Lego set was! I think a long history of tearing things apart to see how they worked started there.
UPDATE: After I looked through the instruction set, I now remember that the car also had seats that adjusted postion forward and backward, and the seat backs changed angles. It also had a “real” rear differential with ring and pinion gears.