It's usually positive, but I seem to get a lot more negative jealousy from people older than me (I'm 23).  From the younger crowd (my age and down), it usually is all positive.
As a nightclub promoter, I'm pretty well known around Tucson AZ, so I've had quite a few occasions of attractive women climbing into my car (of course, not without provoking 

 )
And there is the occasional stop light ricer that wants to race.  I don't, because I know I'll lose...  Makes me wish my little 2.5 was a little faster haha
3.4 996 engine, you'll be mine one day!