This affects the cars stance whether its lowered in the front or in the back
0.5 means front and rear are equal in height. Under 0.5 lowers the front, over 0.5 lowers the back (like Vapid Blade).
<fRollCentreHeightFront value="0.500000" />
<fRollCentreHeightRear value="0.500000" />
These values affect body roll. Some mod cars experience inverse body roll when cornering and braking/accelerating.
Lowering these values fixes this. There is a "break even point" where the body roll turns opposite.