Quote from: Skarg;995415(One of, or I think the) very first world books for GURPS was Autoduel, for roleplaying in the Car Wars "universe". Or is that what you meant by "the later expanded RPG rules"?)

Autoduel was GURPS, CARWARS had RPG expansion rules years before GURPS existed. In addition to expanded rules providing skills and abilities, there was also a road atlas series providing details of the world of CARWARS and a number of published adventures that were much more than just arena duels.

Unfortunately Autoduel is actually one of the weakest GURPS books ever made, I found it very unsatisfying. They would have been much better off tying it directly to CARWARS integrating the CARWARS vehicle rules with GURPS instead of providing a very simplified vehicle system into GURPS (this was before GURPS Vehicles).

HERO System offered their own version a couple years before GURPS as well with Autoduel Champions. It also had issues, but was a far better effort than GURPS Autoduel.