Clever - posting it while I am away
I wouldn't have been anywhere near a clean sweep here, but the nice thing is that a lot of the cars that I wouldn't have got straight away have already been guessed now! I'll fill in some blanks, though:
#6 is very similar to a Land Rover Defender. But I suspect it's not that easy...
#17: Mosler TwinStar, the subject of a former puzzle of mine
#19: Bentley BY 8.16 Hunaudières