NHTSA’s mission is to prevent motor vehicle crashes and reduce injuries, fatalities, and economic losses associated with these crashes. To carry out this mission, NHTSA conducts a range of safety-related activities, including: providing guidance and other assistance to states to help address setting vehicle safety standards; investigating possible safety defects and taking steps to help ensure that products meet safety standards and are not defective (through recalls if necessary); collecting and analyzing data on crashes; and traffic safety issues, such as drunk driving and distracted driving. NHTSA also develops uniform guidelines for states’ highway safety programs. In the past, these guidelines were referred to as standards, and if a state failed to implement these standards, DOT could withhold a percentage of federal-aid highway funds apportioned to the state. As shown in figure 1, this authority changed in 1976 when legislation limited NHTSA’s authority to withhold apportioned funds. Since that change, states have been able to choose whether or not to follow the guidelines in developing their highway safety programs. NHTSA’s guideline on state motor vehicle inspection programs, included in its Uniform Guidelines for State Highway Safety Programs, recommends that states should have a program for periodic inspection of all registered vehicles to reduce the number of vehicles with existing or potential conditions that may contribute to crashes or increase the severity of crashes that do occur, and should require the owner to correct such conditions. We found that 16 states operate periodic motor vehicle inspection programs. See figure 2 below. These states develop the specific rules that govern their programs. For example, 11 of the 16 states with inspection programs require an annual vehicle safety inspection, three states require a biennial inspection, and two states require time frames other than annual or biennial. Further, some states allow certain vehicles to be exempted from the safety inspections, such as newer model vehicles (up to 5 years from the model year) or vehicles at least 25 years old and registered as historical vehicles. Some states couple the safety inspection with emissions inspections. Vehicle safety inspection programs are administered by the state motor vehicle administration, department of transportation, or law enforcement agency, and in all of the states, except Delaware, state-licensed private inspection stations perform the inspections. The number of these private inspection stations per state ranges from around 295 (Rhode Island) to 17,000 (Pennsylvania). With a few exceptions, states do not limit the number of private inspection stations that may participate in the safety However, inspection program; it is typically a market-driven process.states require these inspection stations to obtain certification or licenses from the state. Delaware operates four state-run safety inspection sites. The fees charged to vehicle owners for safety inspections are mostly set by the state, though five states allow a market-driven fee which is set by individual inspection stations. State officials we spoke with provided information on the fees collected from drivers at the time of inspection. These fees ranged from $0 (Delaware) to $55 (Rhode Island, but this includes an emissions inspection). In addition to the guideline for states on periodic motor vehicle inspection, NHTSA has issued Vehicle In Use Inspection Standards, which set inspection criteria for several vehicle systems.system standards for brakes (hydraulic, vacuum, air, electric and service brakes), steering, suspension, tires, and wheel assemblies. For example, the standards specify that tread on a tire shall not be less than two thirty– seconds (2/32”) of an inch deep and provides an inspection procedure for examining the tire for this depth. These minimum standards apply to all states that choose to implement a vehicle safety inspection program. However, states with programs include more vehicle systems in their inspections than are specified in the standards. For systems not covered by these standards, each state determines what will constitute a passed or failed component. Examples of other systems generally incorporated into state vehicle safety inspections are lighting (such as headlights, brake lights, and turn signals), seatbelts, horns, windshields, wiper blades and the vehicle’s undercarriage. According to officials in 15 states with existing vehicle safety inspection programs whom we interviewed, these programs help improve the condition of vehicles; these officials point to data on the number of failed inspections as evidence of the safety benefit of these programs. Officials whom we interviewed from all 15 states said their programs help identify vehicles with safety problems and remove these unsafe vehicles from the roadways or compel owners to make repairs that otherwise might not be performed. Most of these states (12 of 15) collect data on the number of vehicles that fail inspection—the failure rate—and officials from 9 of these states cited their failure rate data to demonstrate the effectiveness of their programs. For example, Pennsylvania officials provided 2014 data showing that more than 529,000 vehicles (about 20 percent of the state’s 2.7-million registered vehicles) underwent repairs in order to pass inspection after initially failing. Virginia officials told us they believed that their state’s roadways were safer because their program identified safety problems in over 1.4 million—or 19 percent—of the state’s 7.5-million vehicles, in 2014. According to Virginia officials, 700,000 of those vehicles were rejected for brake-related issues such as worn, contaminated, or defective linings or drums, disc pads, or disc rotors. Safety problems most frequently found in other states in 2014 included: problems with glass, which resulted in 47,172 failed inspections in Utah; malfunctioning brake lights, which resulted in more than 13,000 failed inspections in Delaware; and tire deficiencies, which resulted in almost 6,000 failed inspections in Rhode Island. Additionally, officials in three states said that vehicle safety inspections are valuable because the average age of passenger vehicles is increasing and, in some areas, weather conditions and roadway treatments such as salt may contribute to vehicle deterioration. For example, Rhode Island officials stated that their inspection program is necessary in part because the state’s snow and icy weather requires road treatments that can corrode a vehicle’s chassis, steel brake lines, suspension, steering linkages, and ball joints. Further, these officials said that their inspection program is important because vehicles are staying in service longer—with some cars accruing more than 300,000 miles— exposing vehicle systems to more use and risk of developing safety issues. DOT data show that the average age of passenger vehicles has consistently increased from 1995 to 2013, from an average age of 8.4 to 11.4 years. Similarly, Vermont and West Virginia officials told us that their states’ snow and associated road treatments, coupled with rough terrain and poor roadways, increase vehicle deterioration. They said that their programs mitigate seasonal weather challenges by reducing the number of unsafe cars in use. Despite the consensus among the state inspection program officials we interviewed that these programs improve vehicle condition, research remains inconclusive about the effect of safety inspection programs on crash rates. There is little recent empirical research on the relationship between vehicle safety inspection programs and whether these programs reduce crash rates. What is available has generally been unable to establish any causal relationship.on vehicle safety inspection programs in 1990, there have been three econometric studies conducted examining the relationship between vehicle inspections and crashes in the U.S. and three studies examining these programs in other countries. Among the three studies of U.S. vehicle inspection programs, none were able to establish a statistically significant effect of safety inspection programs on crashes involving either fatalities or injuries. Specifically, the studies examined crash rates in all 50 states and did not find statistically significant differences in crash rates in states with inspection programs compared to those without. International studies have also not been able to establish a link between Since GAO last conducted a review safety inspection programs and crash rates involving either fatalities or injuries. For example, only one study suggested that safety inspections potentially reduce the likelihood of crashes, but noted the magnitude of the reduction could not be clearly established.information on each of the studies. See appendix III for more While our literature review did not yield any studies establishing that vehicle safety inspections reduce crashes, this does not necessarily demonstrate that inspections do not have such an effect. Nationwide studies involving crashes related to vehicle component failure are hindered, in part, due to a lack of nationwide crash data. There is no comprehensive database for all police reported crashes in the United States. NHTSA maintains two data sources that capture some vehicle crash incidents related to component failure. NHTSA’s Fatality Analysis Reporting System (FARS) is a census of all fatal traffic crashes in the United States that provides uniformly coded, national data on police- reported fatalities, and contains information on crashes in which vehicle component failure was noted, but is limited to crashes involving fatalities. NASS-GES is a nationally representative sample of police-reported motor vehicle traffic crashes, which is also uniformly coded and contains information on crashes in which vehicle component failure was noted in the police report. However, the sample is not set up to be representative at the state level; therefore, it cannot be used to compare states with and without safety inspection programs. Some researchers have used FARS in their analyses in order to perform state-by-state comparisons, but detecting the effect of inspection programs on crash rates is difficult because few crashes involve fatalities, and relatively few of those fatal crashes are noted in police reports as having vehicle component failure as a potential contributing factor. According to our analysis of NHTSA’s NASS-GES crash data from 2009 through 2013, crashes with noted vehicle component failure constituted around 2 percent of all crashes nationwide. We also found that the three most common failures were related to 1) tires, 2) brakes, and 3) steering. These categories make up the majority of failures reported with the next biggest category being “other.” (See fig. 3.) These components are inspected as part of all state inspection programs.