Alright I figured out the problem. It had to do with getting a child object from the model that was imported as a "car". This was code that was in the constructor that I didn't include in my previous post because I didn't think it was important (oops.):
Code:
self.frontWheels = self.tempCar.getChild( '0' + str(randomCar) + 'tyresBack-OFFSET' )
self.backWheels = self.tempCar.getChild( '0' + str(randomCar) + 'tyresFront-OFFSET' )
this needed to be changed to:
Code:
self.frontWheels = self.getChild( '0' + str(randomCar) + 'tyresBack-OFFSET' )
self.backWheels = self.getChild( '0' + str(randomCar) + 'tyresFront-OFFSET' )