Quick look at the second type of car, for the game: The van!
I'm done now with the high-poly modeling, so I can go on to create the game-ready, low-poly versions, next.
Again, you'll notice lots of details missing from the high-poly models (i.e. windows, lights, etc.). That's because those would be a pain to model in the hi-res subdivision mesh; it's just so much faster to paint those things on, in the texturing step.
Similarly, I've modeled the interior completely separate from the rest of the car: Cutting holes for doors and windows is so much easier/faster to do with the low-poly mesh, later on, so combining interior and exterior is going to be the final step.