MUST.... RACE.... YOU.
 
rFactor is the ****.  I roll the MR2 mod from F1Elites and the Project D 2.3.
 
Challenge?

Trav is correct, but i didnt want to go into it that far in detail due to the risk of losing everyone.

It is true that the relationship between the normal force N (which is the force reacting to the weight of the car) and the force created F is not linear. It the increase of force per increase of weight lessens with greater and greater weight.
If this was not so a heavy car would be able to travel a corner as fast as a car that weighs nothing.

I was looking for a graph to show this, but google failed me.
Any other vehicle dynamics questions feel free to ask me.  

TRD2000

ummm what's a coefficient of "grip"?

grip = force (downward load or weight) X the coefficient of friction

the coeff of friction is determined by the chemical composition of your tires and their heat.... and the surface you're on.

the grip doesn't drop off with load... the braking load gets higher and overcomes the grip.

Sorry to cause any confusion, by coefficient of grip I was referring to the coefficient of friction. It is not constant as many believe.
 
If anyone is ever interested in car dynamics, I highly recommend reading Tune to Win - Carroll Smith, and Drive to Win also provides an insight to this area and gives much information on race car driving.