i doubt you'd find a 93 GTSt with 40000 genuine kms... again as Sumo said, kms arent a proper indicator, try compression tests to check the engine and drive the car for a little bit with an experienced friend / mechanic to help pick out problems with gearbox shifting etc.. when i bought mine, i had it inspected by a performance shop.. even had it on the hoist and also removed all the interior trim in doors, boot etc to check for accident damage..
basically there are lots of imports out there, and most of them would have small little irritating problems but thats part of owning an import.. its something u live with i guess