I am cool,
I am really glad you are trying to get make a car using the engine.
but I believe you have an idea that will lead you to a dead end.
Using joint in a naive way to make a fast moving body is not as simple as contention joints.
I said using the car joint is the way to make a realitic car, but there are way to make it, it is not jut conecting pieces together and hoping for them to work.
the problek is that teh very high mass ration that teh tire an dteh car body have lead to a very poor joint solution. so somethong has to be done to make the engien to produce the most effecient and meaninful solution.
Even if you manage to get it work correctly at l;ow speed you will still have to deal with the fact that the joint will not be able to keep the tires together at high speed.
the way I handle that is 1.53 was by susampling the engine update for cars only, in 2.0 is by projection.
at the very least you will learn how to made stable and how the wheels joint are implemented.
The car joint is the CustomMultiBodyVehicle, see the demo so tah you can see how it is put together.
The car joint is a hierarchy of joint,
the parent is the car body, which is a unilateral, and it have children joint, for each tire, including differential joints.
please check it out and then you can make you own,
the worst thing you want to do is using plane ordinary joints to connect tire to the car body, it will not work.
That approach will only work for Academic projects where the interest is steady state simulation and real time is not as important.