Cool that's all you really need and your cell phone flashlight.
I used PS to overlay two images shot with different settings to get that picture with the camera in the exact same position on a tripod.
Location: any place where there is nothing but darkness or as far away from any city or natural light that might appear in the view finder. Use a flashlight to help you focus in the dark.
1st picture settings (starry background):
Manual
30 second exposure
F/4.5
ISO 1600
WB auto
2nd picture settings (shining white light on the paint):
30 second exposure
F/4.5
ISO 100
WB auto
The trick for the 2nd picture is as soon as you press the shutter, bust out that flashlight and walk around the car within those 30 seconds while flashing the light at the paint.
Try to keep the actual light source aimed away from the camera lens. I usually just hold the light in front of me and walk at an angle so that the camera can still capture the light reflecting off the paint. Then blended the two images together. I'll show you the two pics when I get home.