Racecar robot moves in a rectangular path

[AlonFlor]

Essentially the same issue as #2851.

I took the four-wheeled racecar from here and modified the code and the urdf, both are attached in modified_racecar_files.zip.

I made sure to disable the cone friction, and it didn't help. The trajectory looks like this:

The video of it is here.

For comparison, I managed to get the r2d2 robot that came packaged with PyBullet to go in circles rather than rectangles. My code for it is in hello_pybullet.zip, and the trajectory looks like this:

The video is here.

Without disabling cone friction, the r2d2 robot also had a rectangular trajectory. For some reason, the "disable cone friction" fix solves the problem for the r2d2 robot but does not solve the problem for the race car.