Porsche 928 - excellent GT with a great sound. Auto gearbox from a Mercedes with kickdown to first capability. Really cool car
Nissan 300zx - everyone wants the manual so the auto should be available at your price range
Acura Legend Coupe - very nice and rare
Lexus SC400 - that V8 definitely has some punch
Mercedes 400e - Plenty of V8 power I personally seen it go well over 140. Charming and reliable, loads of character
These can all be had for under $4k. It will be a little more challenging finding the 928 as their values are starting to creep up!
