Much like similar rallies on Earth there is a category in the Martian Polar Pavonis Rally for support vehicles. Uniquely in this race the support vehicle must transport a tanker with 20,000 litres of refined Titan Hydrocarbons on board.
This is a throwback to the origins of the race commemorating the emergency transport of oxygen between Schmit Ice Base at the Southern pole and the MSA Research station at Pavonis Mons, near the Martian equator in the first years of settlement.
Like all martian vehicles they are powered by Hydro-Carbons mined by Octan and other companies from the huge Hydrocarbon lakes on Saturn's moon Titan.
Current terraforming estimates are that it will take another five centuries of heavy industry and ultra fuel burning cars for Mars to reach a level of atmospheric pressure where liquid water can exist on the surface.
This is the Octan Arrowhead Mars Support Truck Version 3 (MST3) it won it's category in the 21st running of the Polar Pavonis Rally.
Thanks for the kinds words everyone. The wheels seem very popular, 2 of the wheel hubs came in white only in the Star Wars UCS Y-Wing, no I don't have two, I bought these a couple of years ago at a LEGO fan event.
I only figured out I didn't have any tyres for them when this was almost finished, but luckily discovered the small caterpiller tracks would stretch over them. The final result is better then I ever hoped for!