you need to know if the wheel transforms are relative to the chassis transform or if they are relative to the world origin in 3ds. You then will need to treat them the same in your code.
You have it implemented as if they are relative to the world origin. You can switch it to relative to the chassis to see if it works like this:
connectionPointCS0 =(btVector3(matWorld._41, matWorld._42, matWorld._43)) + (btVector3(chassisWorld._41, chassisWorld._42, chassisWorld._43));
if that makes the wheels display in the correct place, then essentially you've imported the model with a bone hierarchy that will need to be updated every frame or at least every time the car changes position or rotation.