Gee's man, can't believe you got hit by a car but its good to hear you didn't get hurt too badly.
Your vents, I would say the only thing I can think of is paint stripper... I don't think it will damage the chrome but if it did, you got nothing to loose because you were going to repaint them from the start and sanding the paint off will defiantly damage the chrome. But i really don't think it will do anything to it anyway.
I say go for it and give it a shot, just be careful with paint stripper. Its nasty stuff so make sure you wear heavy rubber gloves.
Get paint stripper and put it on really thick. Once the paint stripper has worked (about 2 hours i think) get a high pressure water cleaner to wash off the stripper. You might have to repeat the process again because there will always be a bit of paint left on there from the first time.
Hope it helps...
Johno.