When a car collides head-on with another car or some other yielding or unyielding object the subsequent motion of the car can be predicted by using the laws of physics. This is first done in the paper in a gross way by means of a simple graphical method. The analysis is then refined to take into account the non-uniformity of crushing strength found in real cars. The motion of the occupants using a simple model completes the picture. It is shown that for older cars, which have no air bags and elementary seat-belt systems, strike with the steering wheel or dashboard is almost inevitable at the speeds considered in the paper. The advice to drivers is to drive at a less-than-average speed and to occupants to set the seat back as far as possible.