As jb said, springs are very dangerous. Most people do not realize how heavy a garage door is until they release the springs, (I almost lost a finger), when the door came crashing down.
All garage doors should have safety cables on all the springs.
I would call a garage door company and have them evaluate the problem and fix the door. Have them install the safety cables if you do not have them. The risk of injury and the damage they can do to your car is far too great to ignor!