Great new models, I was impatient for this update :D, but you should limit the RPM of the WheelColliders! For my game I use an AnimationCurve to reduce the torque as the RPM goes up. If you don't do that, the car keeps accelerating for a while after you release the key. You can use this calculator to determine the max RPM of each car: http://www.endmemo.com/physics/rpmlinear.php It's also important to not to apply all the torque from the beginning. Actual cars gradually increase the power even if you put the pedal to the metal.
And what happened with the door handles of Model S? they are not animated anymore.