Difference between CLI and GUI?

Hello,

The GUI and the CLI version seem to have a different accuracy, even when using the same physics iteration constant. I tried to reproduce that difference, and also did it:

First, I opened the Demolition demo, and set the fast-physics-iteration from 15 to 5.

I then let the car drive for a couple of times within the GUI version; In 74 cases, the vehicle managed to crash into the pile before touching the ground after the jump; In 44 cases it didn't. The path after the jump was often random, sometimes it turned or hit the blocks after landing, sometimes it went straight ahead.

Then I tested the same file within the shell. After thirty times of driving, the Braitenberg vehicle didn't hit the pile once. Furthermore, the vehicle always took the same path - It drove onto the left part of the ramp, then passing the pile at the left side and driving on straightforward.

Does anyone know what is happening here?