Study: Battery electric cars have a slightly lower crash risk than combustion engine cars

According to a recent Finnish study, fully electric cars are involved in slightly fewer injury crashes than traditional combustion engine cars. Despite technological advances, however, the injury crash risk of passenger cars has not decreased in Finland in the last ten years.

The purpose of the study conducted at Aalto University was to determine whether there is a difference in the crash frequency of passenger cars depending on their power train. The data consisted of injury crashes compensated by motor insurance in 2019–2023. The study included passenger cars registered in 2012 or later.

As a secondary finding, it was found that passenger cars in Finland are no safer today than they were ten years ago. The crash rate of battery electric cars representing the latest technology was 20% higher in relation to kilometers driven than that of combustion engine cars of the same age ten years ago.

Passenger car safety improved rapidly at the beginning of the millennium, but now it seems that this positive development has come to a halt. Active safety systems that assist drivers are becoming more common in the car fleet, but safety developments over the past ten years seem surprisingly modest, says Tapio Koisaari, Head of Technology at the Finnish Motor Insurers' Centre, who conducted the study.

- Road transport is undergoing a transformation with the advent of autonomous driving and electrification. At Aalto University, we are addressing the questions raised by this transformation through research, with an emphasis on collaboration with various partners, says Risto Ojala, Associate Professor at Aalto University.

Power source does not affect crash frequency

The study found no significant differences in crash frequency between vehicles powered by different energy sources. The crash frequency per kilometer driven was approximately 15% lower for fully electric cars than for combustion engine cars. There was no difference between hybrids and combustion engine cars. The lower crash risk of fully electric cars is likely related to where the cars are driven, rather than the technology used in the vehicle.

No direct conclusions can be drawn about vehicle safety from the crash rates. Fully electric cars are currently driven more than combustion engine cars (20,600 vs. 15,800 km/year), and driving is more concentrated on highways than in urban areas. There are fewer personal injuries per kilometer on highways than in urban areas, so the driving environment at least partly explains the slightly lower number of crashes involving electric cars, Koisaari emphasizes.

Exceptionally extensive Finnish registry data

The study combined vehicle, insurance, and crash data from 2019 to 2023. Almost all (97.6%) passenger cars registered for private use in Finland in 2012 or later were included in the study. The cars included in the data traveled a total of 76 billion kilometers during the study years and were involved in over 11,000 injury crashes. The research data was processed by Timo Kari from the Finnish Motor Insurers' Centre.

The data was used to calculate personal injury rates for four different types of cars: hybrids, plug-in hybrids, fully electric cars, and traditional internal combustion engine cars. Only crashes in which the injured person was in a motor vehicle and the cause of the crash belonged to one of the above-mentioned car groups were included in the study.

The crash rates for electric and hybrid cars were compared to those for combustion engine cars, but the comparison was not made directly. Instead, the used calculation model first controlled for confounding factors that influence crash frequency, such as vehicle size (and intended use) as well as characteristics of the vehicle’s driver (age, gender). The regression model used in the calculation was developed by Tero Vahlberg from the University of Turku.

Abstract of the study: Injury crash risk of battery and hybrid electric passenger cars
Request a copy of the study from its author, Tapio Koisaari.

Additional information:

Finnish Motor Insurers' Centre
Head of Technology Tapio Koisaari: +358 40 450 4782, tapio.koisaari(@)oti.fi   
Communications: +358 40 450 4700, viestinta(@)vakuutuskeskus.fi