Car Wars focuses more on the vehicles as far as the rules are concerned, or I should say, all versions do that except maybe the latest. I'm not sure if they've changed the rules as I don't own the latest version. You do have rules to deal with the individual, but they're pretty basic, because Car Wars focused on the cars, motorcycles, trucks, etc.
AutoDuel on the other hand, focused on the individual or Duelist first and then included vehicles. You end up with a better defined character with AutoDuel than Car Wars.
But they both have their appeal!