Yes, of course, I am sure Lakey and Nick can do this one evening this week
It takes a lot of time, trial and error and patience to adjust the physics of a car to make it right, and changing all the cars isn't something that would be fisable right now.
Some cars can be disabled by breaking the back wheels, Crown and Marina spring to mind so that feature is kind of already in place.
Like Reg has said, Nascar heat is primarily a 'racing' game, with the damage coming second. I personally think this is as close to real life as you can get without starting completely from scratch on a custom built engine, so just be grateful for what we have now.