To be honest I prefer the original version! BW looks cool but like DubFan said, it doesn't really look like a night shot any more.
I think the original is easily saveable though. I'm at work at the moment so I can't play in photoshop, but basically the exposure is pretty perfect and that's the hard bit to get right.
Personally I'd just darken the sky , probably with a 'multiply' adjustment layer and a graduated layer mask so you leave the car alone. Possibly desaturate a bit too, or maybe actually saturate it more!. For the car I'd just pull all the saturation out of the cyan/blue type area of the spectrum. Dirty and quick but I think on that shot it would work OK. Possibly a quick layers adjustment too, shadows look fine but midtones and highlights might need a little lift on the car.