Edge looping!
That's the key here, at least as long as you're going for highpoly cars. Lowpoly is different, though not too much.
Some people may think that edgelooping is only needed for organics, but that's not true. It's very important with making cars as well, you just tend to use more edge reinforcement with cars.
So I'd recommend you find tutorials on edge looping. Also, don't just search for car tutorials in anim8or. Any car tutorials should work, since all you need is the method. You should be able to translate that method to anim8or pretty easily.