Sport Utility Vehicle (SUV) rollovers continue to cause a substantial number of deaths and injuries each year. According to federal crash data, 10,400 fatalities and 185,000 injuries occurred in rollover crashes in 2000. Most rollovers involve single vehicle crashes in which the vehicle leaves the roadway. Sport Utility Vehicles experienced the highest rollover rates making up more than 36 percent of fatal rollover crashes and 12.1 percent of injury crashes. Combined pickup trucks and vans account for more than 43 percent of fatal rollovers and more than 10 percent of injury crashes. The differential in rollover rates between passenger cars and SUVs/light trucks is a problem that has been recognized by safety and policy experts dating back to the 1970s.

Despite attempts during the past 25 years, the National Highway Traffic Safety Administration (NHTSA) has not issued a standard for rollover propensity. The agency first considered a minimum performance requirement for rollover resistance in 1973 that was based on accident avoidance maneuvers. The proposed rule was dropped because of manufacturers’ questions about test repeatability and the actual need for such a standard. Before the issue of a stability rule was revisited in 1986, NHTSA finalized a regulation, effective for the 1985 model year, that required warning labels on short-wheelbase utility vehicles to alert drivers that these vehicles handle differently than passenger cars. The political nature of the agency is apparent as the requirement contradicted an earlier agency position that argued that rollover cannot be adequately guarded against through the use of warnings.

In 1986, NHTSA addressed the rollover problem in response to a petition from Colorado Congressman Timothy Wirth. Wirth requested rulemaking to establish a minimum static stability factor (half the track width divided by its center of gravity or T/2H) of 1.2. He also requested that stability factor and rollover information be made public. While NHTSA acknowledged a “significant rollover problem” and that a vehicle’s stability factor is related to its overall involvement in rollover incidents, it denied the Wirth petition in December 1987. The agency claimed that addressing rollover based on the stability factor was too narrow an approach and a regulation could result in the elimination of most of an entire vehicle type. While this was NHTSA’s official position, internal agency documents surfaced showing that the agency’s technical staff recommended granting the petition but were overruled by the politically appointed administrator.

After its handling tests of the Suzuki Samurai, Consumers Union, publisher of Consumer Reports, petitioned NHTSA in 1988 to establish a minimum stability performance requirement. The agency granted the petition and eventually issued a proposal in 1992 that indicated it was considering regulatory action to reduce rollovers. Two years later NHTSA terminated rulemaking to develop a minimum rollover performance standard and instead proposed a new labeling requirement that would inform consumers about vehicles’ resistance to rollover. This move was lauded by the industry and severely criticized by safety advocates. NHTSA defended its position claiming that a rollover standard would create significant adverse impacts on both manufacturers and consumers in terms of monetary cost and loss of consumer choice.

Congress stepped in and required the National Academy of Sciences (NAS) to examine the labeling issue before NHTSA could proceed. NAS found that labeling vehicles with summary measures regarding vehicle safety would help consumers, but argued that current knowledge to develop a crash avoidance measure was not sufficient.

In 1996, after it tested the Isuzu Trooper, Consumers Union again petitioned NHTSA to address the rollover problem requesting that the agency create an emergency handling test to rate vehicle performance. In a May 1997 notice NHTSA agreed to initially explore whether it could develop a practical and repeatable handling test. Two years later NHTSA revised its 1985 warning label requirement which became effective for 2000 model year vehicles. The new label updated the previous warning and contained new text and colors in an attempt to provide improved warnings about the increased rollover hazard.

In June 2000, NHTSA finally published a proposal to rate vehicle rollover risk using the static stability factor (SSF) measure. The proposed rule was issued after more than 25 years of rulemaking debate and studies addressing vehicle stability in a regulatory environment only to be held up again two weeks later by Appropriations Committee Chair, Senator Richard Shelby. In a tactic that many claim was aimed at delaying or completely eliminating rollover ratings, Shelby added language to the bill to specifically prohibit NHTSA from finalizing or implementing the proposed rollover rating regulation until the National Academy of Sciences (NAS) studied the matter further. However, as a result of the Firestone/Ford debacle, support on Capital Hill shifted helping to lift the delay imposed on NHTSA’s June 1, 2000 proposed rollover-rating system. On October 6, 2000, the DOT appropriations bill passed the House and Senate. Although it required a nine-month NAS study, NHTSA was allowed to move forward with its proposal.

In 2001, NHTSA finally issued a rule to incorporate a rollover resistance rating for new cars and light trucks into the New Car Assessment Program (NCAP). The agency argued that this information will enable consumers to make choices about new vehicles based on differences in rollover risk and will also serve as a market incentive to manufacturers to design their vehicles with greater rollover resistance. NCAP currently provides consumers with a crashworthiness star rating system to describe the risk of rollover in the event of a single vehicle crash. One star represents a Static Stability Factor (SSF) corresponding to a 40 percent or greater risk of a single-vehicle crash resulting in rollover, while five stars would represent an SSF corresponding to a risk of less than 10 percent. In addition to providing a star rating based on the SSF, the agency will also denote vehicles that are equipped with "electronic stability control" technology which may reduce the risk of a vehicle getting into a rollover.