Like them all, M5's - always loved. Audi's are cool too. Just looked at the porsche's and I would get a convertible one if I was going for the porsche. You could get the new shape M3 for that money.

OR

if your not bothered about it being a sports car you could import a hummer or even a ford F150

sorry for being no help at all. you can get a lot of car for 30k , just wish I had that to spend