I'm usually not a fan of this, but you might look into renting some continuous lighting. The light output must be relatively high because you need to cover a large object. Because a car is so big compared to portrait or small product, it will be invaluable to have an accurate visual idea of how your lighting is shaping up. Also look into Kino flo lights to place inside the car to bring up the interior. Unfortunately, this is expensive lighting gear -- even to rent.
The other option is to shoot using ambient light (as the subject is not moving) and bracket. HDR may not get you the effect you want -- you will probably have to do some detail work in post, but it will be worth the effort if you sandwich exposures that are spot on for isolated parts of the image and then brush these in selectively using layer masks.
It's a tough assignment with many options but the key to getting the exterior right is to use a huge light source. That's what recommends ambient lighting. You might be able to use the sb-910 to highlight individual components of the interior on separate exposures, but I recommend you do this with the windows open, if possible. A studio light on a boom might work for the convertibles, but you did want to consider hard-top cars as well.
You'll probably want to try some options out with your own car before going for the real shoot.
Good luck with this.