What if we were given the ability to make 6x6s with the truck and car bodies. And when I say that, I mean as in functioning suspension, locking diffs, and being driven.
Now before you say that a 6X6 does not fit in with being a car tycoon game. There are examples such as the Mercedes Benz AMG G63 6X6 and the Landaulet which are two examples of production 6X6 trucks.
Dodge had a concept for a 6X6, the Ram T-Rex 6X6.
Some more trucks come from tuner companies:
Ford F150 6X6 “Velociraptor”
Chevy Silverado 6X6 “Goliath”
Ram TRX 6x6 “Mammoth”
Land Rover Defender 6X6
Toyota Hilux 6X6 “AT44x6”
Chevy Silverado 6X6
Jeep Gladiator 6X6 “Hercules”
These trucks add to the fact that a 6X6 could be placed under the clause that a 6X6 would not break the fundamental idea that this is a car tycoon as manufacturers like Mercedes had done so twice. Thus it would not be too far out of bounds, besides, we have race parts, nitromethane, racing slicks, and official LMP styled bodies in the game. Making 6X6s not an unreasonable idea.
This idea may be slated as a DLC just like some other probable suggestions such as diesel, electric motors, other types of engines, and superchargers.