I'm working on a project right now that calls for a time lapse sequence in a car. I decided to take a stab at it tonight, and I must say it was quite fun. I used a D800 with a 24-70mm f/2.8 lens and mounted it on my Manfrotto Neotec tripod. I ended up folding my back seats down and setting the tripod up on them. I used bungee cords to hold the tripod down as steady as possible to prevent camera shake. Although that worked quite well, it turns out that my Manfrotto Grip Action Ball Head isn't quite strong enough to support the D800 and after hitting a few bumps, the camera tilted a bit during the drive. Therefore, I ordered a Really Right Stuff mount for the D800 so that I can switch from the Manfrotto ball head to my Really Right Stuff BH-55 ballhead, which is much stronger and should hold up much better. I also need to lower the camera a bit, as my rear view mirror is too much of a distraction.
In terms of camera settings, I opted to use Interval Timing as opposed to the D800's Time Lapse setting. Exposure was set to 1/2 second, aperture to f/3.2 and ISO at 100. Interval Timing was set to one frame per second. I used Adobe After Effects to render the time lapse video and then Final Cut Pro X to add audio (Close Behind by Calexico) and finalize the video.
Anyway, just thought I'd share. Stay tuned for either the next attempt or better yet, the final cut!!