My '99 Hyundai Accent (82 HP) was named Silver Bullet by friends and co-workers because I drove it like it was some kind of fast sports car (when really 0 - 60 took like 10 seconds...at best) and of course some of them thought it was shaped like a giant Coors beer can.
I named my '03 Cavalier "Speedy" just because it was an ironic thing. Kinda like when you meet a really big person and you find out their nickname is slim.
I didn't give a name to my Sonata...I just called it "the car" "the Sonata" or sometimes "the 'nata"
I named my '06 Mustang "Silver Bullitt" (hence my screen name) because that was the first thing that came to my mind when I saw it on the lot and I thought the name fitted.
I haven't named my '11 yet and I'm not sure I ever will. I just call it "the ride", "my Mustang", "the Pony" and when I'm feeling spunky..."the whip" but no official name as of now.
For Play: 2011 Ford Mustang v6 Premium Coupe w/Pony Package. Stock...for now.
For Work: 2011 Hyundai Sonata SE. The fun daily driver.