Since we're doing nostalgia this month, how about allowing use of the TM1 Speed pack, since it not only provides an easy way of getting the original desert car model/physics into your map (since it uses that TM1 archetype on newly-created maps), but also provides an easy way of getting the original TM1 environment blocks?
(My understanding is that if we use those new TMUF archetypes, there's currently no way of getting the "correct" car models/sounds to show up other than a) forcing players to download extra content (models/skins/.wavs) and setting a map to explicitly use that content, or b) creating an entirely new game mode hosted on a dedicated server for one map.
It just grates on my OCD tendencies to, for instance, use the "coast car" in a map but have it look like the rally car. : p)