As example this veilside-kitted celica:

Now select (with the pollygonnal lasso tool) the car (make sure you don't color windows, and lights, and that kind of stuff:

Make a layer via copy and set the blending option (in the layer menu=> now saying normal so change it) to hard light:

Go to image->adjustments->hue saturation and take colorize and color you car (those were mine setting):

Then you can mess a bit with the levels (image->adjustments->levels):

And ready, looks nice doesn't it?