Frontal & Side Crash Test Ratings
In the frontal crash rating, vehicles are classified by the estimated chance of a life threatening head and/or chest injury for the driver or front seat passenger.
Frontal crash results should only be compared against other vehicles in the same weight class. If a light vehicle collides head-on with a heavier vehicle at 35mph, the occupants in the lighter vehicle could experience a greater chance of injury than the results of this test indicate.
In the side crash rating, vehicles are classified by the estimated chance of a life threatening chest injury for the driver and the rear seat passenger. Head injury is not measured in the side crashes.
Since all tested vehicles are impacted by the same size barrier, it is possible to compare vehicles from different weight classes when looking at side crash ratings.
Drivers and passengers in both the frontal and side crash rating receive a
one to five star rating with five stars 
indicating the best protection.
Vehicles are twice as likely to be involved in severe frontal crashes than in severe side crashes. Test results show the relative crash protection provided to occupants using all of the vehicle's occupant protection equipment. Occupant protection equipment consists of safety belts and air bags. The results do not apply to unbelted occupants.
All vehicles had safety belt systems for all occupants and frontal air bags for the driver and right front seat passenger. The side air bag equipment provided on each tested vehicle is shown to the right of the vehicle's overall score. The side air bag column refers to what was in the vehicle tested and not to options that might be available from the manufacturer.
Also, thigh injury is measured in the frontal crash tests and pelvic injury is measured in the side crash tests. If a high likelihood of a thigh injury or a pelvic injury occurs, the consumer is informed of these possible injuries by an asterisk or a pound symbol respectively.
Rollover Resistance Ratings
Most rollover crashes occur when a vehicle runs off the road and is tripped by a ditch, curb, soft soil, or other object causing it to rollover. These crashes are usually caused by driver behavior such as speeding or inattention. These are called single vehicle crashes because the crash did not involve a collision with another vehicle. More than 10,000 people die each year in all rollover crashes.
The Rollover Resistance Rating is an estimate of your risk of rolling over if you have a single vehicle crash. It does not predict the likelihood of that crash. The Rollover Resistance Rating essentially measures vehicle characteristics of center of gravity and track width to determine how "top- heavy" a vehicle is. The more "top-heavy" the vehicle, the more likely it is to roll over. The lowest rated vehicles (1-star) are at least four times more likely to roll over than the highest rated vehicles (5-stars).
The Rollover Resistance Ratings of vehicles were compared to 220,000 actual single vehicle crashes, and the ratings were found to relate very closely to the real-world rollover experience of vehicles.
Like side crash ratings, it is possible to compare vehicles from different weight classes when looking at Rollover Resistance Ratings.
Some vehicles have Electronic Stability Control, a device which does not affect the Rollover Resistance Rating directly but may reduce the likelihood of a single vehicle crash, and thus, the risk of subsequent rollover. NHTSA notes vehicles equipped with Electronic Stability Control by a symbol next to the Rollover Resistance Ratings.
While the Rollover Resistance Rating does not directly predict the risk of injury or death, keep in mind that rollovers have a higher fatality rate than other kinds of crashes. Remember: Even the highest rated vehicle can rollover, but you can reduce your chance of being killed in a rollover by about 75% just by wearing your seat belt.
