34k miles, significantly under your request but a relevant data point:
Check engine light 10 minutes into my 8th ever track session with the car (each ~20 minutes) turned out to be a coil pack, relatively common and at $100 a relatively simple fix. The light went off after turning the car off and on about 5 times and there were zero drivability issues, although they may occur as the pack degrades due to heat and wear and tear.
Not covered under powertrain warranty but it is covered under bumper-bumper (36k/3yr).
http://www.ft86club.com/forums/showthread.php?t=30879