Me personally, in my own cars:

Jag XJR 150 (sold)
2000 Boxster 151 (wrecked)
2012 Boxster S 165 (track, still own)

Driving other's vehicles:

997 Turbo 180 (track)
Ducati 996 170 (track)
M3 E46 gen 150

As a passenger:

Mercedes SLS AMG 204 on I-25 south of Denver...fastest I've been in anything that doesn't have wings.

I love power, but 2 vehicles that honestly scared me: modified Hayabusa, and a Mercedes C63 AMG with MH kit. 600 ft. lbs of torque in a small RWD car. Every time you'd come out of a corner on the track the rear end would try to pass the front if you mashed it. WITH race slicks on!