Below I am referencing vehicles by class, and as such the speed factors are a suggested min/max ratio based upon vehicle value/design. * cars should go slower on rough terrain, purely because of the low clearance off the ground that would cause drag and damage. (20-40 off-road / 100 - 120 on road) * off-road vehicles should have a good speed off-road (40-60) but that benefit should be reflected in a slower road speed (90-100)* Sports cars typically ride lower that normal cars, and should not be allowed to go 20-25 when driving off-road... but they should have superior road speeds (130-140)* Large trucks are designed to be driven off-road but due to their extra mass should be given a penalty: (30-40 off-road / 80-100 on road)These figures are suggestions for improvement. Comments welcome.