A vehicle's auto rollover rating estimates the risk of its rolling over in a single-vehicle crash, according to an official definition of the term by the National Highway Traffic Safety Administration (NHTSA). It is an important indicator of vehicle stability and safety.
NHSTA has developed a five-star rollover resistance rating system based on data gathered from over 86,000 single-vehicle crashes involving rollovers. Rollover ratings combine two measures. One is a measure of how well balanced a vehicle is when stationary and the other is a measure of how the vehicle performs in a simulated high-speed accident avoidance maneuver.
An automobile with the lowest, one-star NHSTA rating has a rollover risk of greater than 40 percent when involved in a single vehicle crash. In contrast, a vehicle with a five-star rating has a rollover risk of less than 10 percent. Generally, most passenger cars and minivans tend to cluster around the four- and five-star rollover resistance rating range, while most pickup trucks and SUVs tend to have ratings ranging from three-stars to one-star.
Consumers looking to purchase a vehicle can use the NHSTA Rollover Star Rating system to see how well balanced the vehicle is and compare its rollover risk with other automobiles in the same class. Remember, the rating is not a prediction that the vehicle will actually rollover in a crash, but a measure of its risk of doing so.
Increased size, space, and utility are all benefits of owning an SUV. However, due to their generally top-heavy design, they are also known for a higher probability of rollover accidents. As their popularity has grown (and as lawsuits have been filed), auto manufacturers have spent millions of dollars improving SUV rollover safety.
The ratings below are based on model year 2010 SUVs with all-wheel drive (AWD). Of the 2010 SUVs tested by NHTSA, the highest rating achieved was four-stars. Many models received this ranking, and four of the more affordable SUVs are described below.
- Chevrolet Traverse. The 2010 Traverse is the Chevrolet version of the popular GMC Acadia/Saturn Outlook/Buick Enclave siblings. To help keep the vehicle upright, the Traverse comes standard with GM's Stabilitrak Electronic Stability Control system with traction control. In the event of a rollover accident, it has six standard airbags with rollover sensors, as well as curtain airbags for all three rows of passengers.
- Nissan Murano. The Murano has become a popular crossover SUV for the Nissan brand. For 2010, the Murano features Nissan's Vehicle Dynamic Control system to keep its wheels planted on the ground. For rollover protection, all trim levels come standard with roof-mounted curtain airbags.
- Subaru Tribeca. Every Subaru vehicle comes standard with AWD, which can help a vehicle drive with increased stability when compared to front and rear-wheel drive. The Tribeca is no exception. It also comes with Subaru's Vehicle Dynamics Control system and a frame reinforced with high tensile steel. Additional standard equipment includes advanced side curtain airbags with rollover sensors.
- Toyota Highlander. One of Toyota's most popular SUVs, the Highlander features Toyota's Enhanced Vehicle Stability Control and traction control systems, as well as rollover-sensing side curtain airbags for all three rows of passengers.
Rollover accidents can occur in any kind of vehicle, but the rollover rating for sports cars are typically higher than other types of vehicles such as pickup trucks and SUVs. Some cars (like the unrated Porsche Panamera) come equipped with a rollover protection system. Here are the top five rollover rated sports cars.
- Mazda Miata MX-5 Convertible. This affordable two-seat convertible starts at a base price of $21,750. Stability control is only available on the Grand Touring model of this vehicle. The MX-5 only has a 7 percent chance of rolling over in a single car crash, making its rollover rating five stars.
- Mazda RX-8 4-DR. This four-seat coupe is base priced at $26,435. Stability control is available in all of the models except the Sport. This car has a seven percent chance of rolling over in a one-car crash, giving it a five-star rollover rating.
- BMW Z4 Convertible. This powerful vehicle starts at a base price of $50,400. The Roadster model features a rollover protection system. This vehicle has an eight percent chance being in a rollover car accident, which gives it a five-star rollover rating.
- Ford Mustang 2-DR. This timeless classic is base priced at $20,430. This vehicle has an eight percent chance of rolling over in a one-car crash, giving it a five-star rollover rating.
- Honda S2000 Convertible. This two-seat roadster starts at a base price of $34,995. It has an eight percent chance of rolling over in a single car crash, which gives it a perfect five-star rollover rating.
Rollovers account for 45 percent of all pickup truck deaths, so the National Highway Traffic Safety Administration's rollover rating for trucks should be an important factor in any purchase decision. A high center of gravity and/or narrow track width (distance between the right and left tires) make a rollover accident more likely. Fortunately for consumers, the pickups with the best rollover ratings also have the highest overall consumer ratings.
For 2010, the top five rollover rated trucks are:
- Chevrolet Silverado 1500. The Silverado earned four-star rollover ratings for both two and four-wheel drive models.
- GMC Sierra 1500. The Sierra, a more upscale version of the Chevrolet Silverado, is identical mechanically to the Silverado.
- Ford F-150. The best-selling F-150 pickup rates four stars for the 2-wheel drive model, but only three stars in four-wheel drive.
- Dodge Ram 1500. The Dodge Ram also rates four stars for the two-wheel drive, and three stars for four-wheel drive.
- Toyota Tacoma. The best rollover rating on this list (four stars, with only a 14 percent chance of rollover), make the Tacoma worth considering if a compact pickup will do.
According to tests run by NHTSA, most vans have rollover ratings between three and four stars, with a 15 to 30 percent chance of rolling over. Vans tend to be more vulnerable to rollover than passenger cars because of extra weight behind the rear axle. Here are five of the safest vans when it comes to rollover:
- Nissan Quest. The van least likely to roll over in a single vehicle accident is the Nissan Quest. It earned four stars with just a 12 percent chance of rolling over and a static stability factor of 1.36.
- Kia Sedona. The Sedona did well in testing, getting four stars for just a 13 percent chance of rolling over. The Sedona had a static stability factor of 1.31.
- Hyundai Entourage. With numbers almost identical to the Sedona, the Entourage also has a 13 percent chance of rolling over and a static stability factor of 1.31.
- Honda Odyssey. The Odyssey checked in with four stars, a 14 percent chance of rollover, and a 1.30 static stability factor.
- Toyota Sienna. Also performing well was the Sienna, which also earned four stars. The Sienna has a 15 percent chance of rollover and a static stability factor of 1.25.
Hybrid owners want to help protect the environment, but not at the risk of endangering their families. Hybrid cars are put through the same rigorous testing as any other vehicle. Listed below are the rollover ratings for hybrid cars (2009 models).
- Toyota Prius. The Prius earned a four-star rating in two-wheel rollover tests.
- Honda Civic Hybrid. Civic earned a four-star rating in two-wheel rollover tests.
- Saturn Vue Hybrid. The Vue earned a four-star rating in two-wheel and four-wheel rollover tests.
- Ford Escape Hybrid. The Escape earned a three-star rating in two-wheel and four-wheel rollover tests.
- Cadillac Escalade Hybrid. The Escalade earned a three-star rating in two-wheel and four-wheel rollover tests.
Passenger cars have about a 12 percent chance of rolling over, according to NHTSA, which provides easy-to-access rollover ratings for sedans on safercar.gov. Here are five of the safest.
- Volvo S60. Volvo has a reputation for being a leader in auto safety, and the S60 is no exception. Rolling over just nine percent of the time during intense testing, the S60 earned five stars, the highest possible rating. It had a static stability factor of 1.49.
- Hyundai Genesis. The Hyundai Genesis won five stars from NHTSA. The Genesis checked in at nine percent with a static stability factory of 1.48.
- Honda Accord. The Accord also performed exceptionally well in rollover tests executed by NHTSA, earning five stars. The Accord has only a nine percent chance of rolling over, and a static stability factor of 1.48.
- Nissan Maxima. Although it did not do quite as well as some of the other cars on this list in rollover tests, the Maxima still earned five stars from NHTSA, with only a 10 percent chance of rolling over and a static stability factor of 1.45.
- Buick Lucerne. The Lucerne performed similarly to the Maxima on rollover tests, getting five stars, with a 10 percent chance of rolling over and a static stability factor of 1.45.