"Weight is a big factor," says Matt Moore, HLDI vice president and an author of the report. "Hybrids on average are 10 percent heavier than their standard counterparts. This extra mass gives them an advantage in crashes that their conventional twins don't have." Moore added that other factors such as the drivers’ habits may contribute ‘noise’ to the result, but researchers have included controls to mitigate the effects of these factors on the final results.
However, there is not so positive news with regards to the pedestrian. A separate HLDI study including 17 hybrid and non-hybrid versions of the same vehicle shows that on average, hybrids are 20% more likely to be involved in pedestrian accidents compared to their conventional versions. “When hybrids operate in electric-only mode, pedestrians can’t hear them approaching, so they might step out into the roadway without checking first to see what’s coming,” Moore explained.
The issue has already been pointed out by the US National Highway Traffic Safety Administration, which pushed for a law demanding that all hybrid or electric vehicles (EV) emit a standard warning sound to warn pedestrians of their presence. Toyota and Lexus had announced that they will fit all of their EV and hybrid models with a synthetic motor sound alert that will emit a humming noise when the car is operating on solely electric power.