I know there's the tank and the advanced tank (latter of which might as well be considered post-endgame tier) both with much larger equipment grid but those are slow combat vehicles. I'd really enjoy a more expensive version of the regular car so I can put in some extra engines and a proper power source. maybe some extra roboports for giggles, as I use my car a lot to move myself and some equipment around my base.
either that or reduce the size of the "additional electric engine" equipment, as 4x4 is huge.
(I know I can change the values in the files... and I did, because I'm a cheater. but a legal option would be cool.)
as a related suggestion, how do you guys feel about a new kind of equipment that increases cargo size? I think it'd be nice for both the car and cargo trains.