These new shots look great! I agree with Untz, a seperate layer for the city lights might help a little. Looking at your EXIF on flikr, try going to a smaller aperture (f11 or f16). This will make the "starburst" of the city lights more of a sharper shape. Raise the ISO a little bit to compensate.
OH! Also, if you can, find a way to wet down the asphalt around the car, it will really make the photo pop. If you have one of those plant sprayer things they work out great for this. Night time car photos look so good with a wet ground. For example:
VR4 Sunset by
Nathan McCord, on Flickr