Start by fixing the origin to between the back wheels, with the car facing right which is the default direction in GameMaker (default direction '0' means right).
Cars steer with their front wheels - so change the origin after you've tried it between the back wheels to the front, to see how this impacts on steering.
|objCar||Key Down → Up event|
|objCar||Key Down → Right event|
|objCar||Key Down → Left event|