Simple physics setup not working, any ideas?

Hi all,

I have recently tried some experiments using the BGE, but I have run into some strange issues and I have no idea what the problem is.

I have uploaded the file here: http://arjanhouben.nl/cartest2.blend

In the script ‘car’ on line 65, I have added an angular motor. It all seems simple enough, except for the fact that the car completely freaks out whenever this motor is attached…

any ideas would be greatly appreciated!