Night shots are cool and also tricky! I think you need a longer exposure time which is tough on the beach because the wind can move a camera and tripod enough to make the picture look blurry. It also help to have some supplemental light that you can "paint" the vehicle with. A lot of times if I want it to look natural I'll do a flashlight with some kind of diffuser on it to soften the light. You can just hit the vehicle in short bursts to add just a little light on the subject.
