The growing popularity of hybrids and electric vehicles in the U.S. has raised questions about whether they might pose a different crash risk than conventional vehicles. In particular, there have been anecdotal reports of fires associated with the battery system in these advanced fuel vehicles. The objective of the study was to characterize the factors that influence the risk of serious to fatal injury in U.S. hybrid and electric passenger vehicle crashes.

Our approach in this study was to compare the crash performance of the conventional passenger vehicle fleet with hybrid/electric passenger vehicles in the U.S. The study was based upon the analysis of three U.S. crash databases:​ the Fatal Analysis Reporting System (FARS), the National Automotive Sampling System / Crashworthiness Data System (NASS/CDS), and the National Automotive Sampling System / General Estimates System (NASS/GES). Cases recorded by the databases between the years 1999 and 2013, and involving passenger vehicles model year 2000 and newer were extracted from all three databases.

Hybrid vehicles constituted less than 1% of the total vehicle population in all three databases. FARS contained no fatalities in electric vehicles, and less than 0.01 % of cases in NASS/CDS and NASS/GES involved electric vehicles.

The incidence of fire was lower for hybrid vehicles than the conventional fleet in all three databases. Fatal crashes involving fire constituted 2.6% of hybrid vehicle cases and 4.4% of conventional vehicle cases. No cases of fire or electric shock injury associated with hybrid vehicles were found in NASS/CDS. Only 1 case of a hybrid fire was found in NASS/GES and 5 cases of hybrid fire were found in FARS. No fires involving electric vehicles were found in any of the three databases.

Similar crash characteristics were found for both hybrid and conventional vehicle populations. Median longitudinal delta-V was 18 km/hr for hybrid vehicles and 14 km/hr for conventional vehicles. Hybrid vehicle occupants were found to have higher risk of AIS2+ upper extremity injury but lower risk of AIS2+ lower extremity injury than conventional vehicle occupants. Similar risk of AIS2+ head and chest injury was observed between the two groups.

The most notable difference between hybrid vehicles and conventional passenger-vehicles was that occupants of hybrid vehicle were more likely to be older than occupants of conventional vehicles. In FARS, the median age of fatally injured hybrid vehicle occupants was 59 years versus 36 years for conventional vehicle occupants. In NASS/CDS, the median age of hybrid vehicle occupants was 42 years and the median age of conventional vehicle occupants was 29 yrs. In NASS/GES, the median age of hybrid/electric vehicle occupants was 44 years, as compared to the median age of 32 years for conventional vehicle occupants.

The present study characterized the crash and occupants of hybrid and electric vehicles. The comparison between hybrid and conventional vehicle crashes showed little difference in the crash performance and injury outcome between the two groups. The incidence of fire was actually lower in hybrid vehicles than in the rest of the fleet.