This is a toy Mobil One Racing tractor trailer made by Hot Wheels. It is just under 14 1/2 inches long and based off a Kenworth T2000. It is diecast. The rear door opens to load the #12 Jeremy Mayfield race car into it (sorry, race car not included). It is very well detailed, and the trailer does not detach from the tractor.
I don't believe this was ever played with. There is some minor storage type rubbing on it, but it is in very good condition.