I was never able to find this game that I played a demo of
RTS game +- 10 years old
Post apocalyptic desert setting, very mad max-esque as you would mount up all your infantry in vehicles for an attack to cover long distances quickly
Graphics similar to KKND
Base building was minimum
Vehicles that could mount infantry in them, different coloured skins of a unit that would come with different weapons (and stats I think), units had ammo restrictions (and possibly fuel)
In the demo you were a red police themed faction - you had armoured swat guys, police squad cars, battle vans
enemies: blue grease monkey themed faction (they were guys in overalls and sunglasses that used mostly bikes and shotguns), green sludgy type aliens, orange raider-fire obsessed guys, I think there was a purple magic/cult/demonic type faction as well