Keep the dat file original and put updates loose in the car folder.
That way you can always revert back to the base car.
And yes you can layer all you want as long as you save as bitmap max 24bits (winmip can't handle more)
Ahh yes, I see that`s what hagapito40 said too (regarding not putting the .mip back in the .dat) when I re-read his post. Ok thanks MECH. I`ll give it a go and hopefully get a nice custom helmet for the 67`s.