[ODE] FDir1 and Slip for car wheels

[Arturo Colorado Garín]

Hi!

I'm trying to model a car. Depending on the friction I use for wheel-ground
contact, two things happen:

1) Low friction: the car skids correctly in a tight turn but its motor
wheels (that is, the wheels that are connected to the motor) also skid when
accelerating (even when not turning).
2) High friction: the motor wheels don't skid anymore but the car flips over
very easily when turning (Note: I've already lowered its center of mass).

The behavior I want is: motor wheels don't skid when accelerating, and car
tends to skid instead of flipping over when turning.

I've tried to use the dContactFDir1 flag to achieve this behavior. On each
contact, I set FDir1 to a unit-length vector longitudinal to the wheel, mu
to a relatively high value and mu2 to a low value. But this doesn't seem to
do anything, it looks like it always takes mu and ignores mu2. ¿Has anyone
had success using dContactFDir1 flag?

I've also tried dContactSlip2 flag as explained in the documentation.
Although it helps in making the car to skid instead of flipping over, I'm
not satisfied with the results (it makes the car to behave a little like a
hovercraft).

Thanks for your help.

--Arturo Colorado