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By Geoffrey Styles on Nov 21, 2013 with 5 responses

Are EVs More Prone to Fires Than Gasoline Cars?

Concerns Prompted by Tesla Fires

Several vehicle fires involving Tesla’s new high-end Model S sedan have attracted a great deal of media scrutiny. Two of the three reported incidents are now under investigation by the National Highway Traffic Safety Administration (NHTSA). Yet while the company’s founder, Elon Musk, is certainly correct in indicating that gasoline vehicles are involved in the overwhelming majority of vehicle fires, including most of those resulting in fatalities, the statistical comparison he has provided in interviews got me curious enough to track down the data for myself.

How Often Do Gasoline-Powered Cars Catch Fire?

The statistic that caught my attention was that Tesla suffers an average of one fire per 6,333 cars, versus a rate of one fire per 1,350 gasoline-powered cars. I’ve been driving for four decades and have probably observed several million cars on the road in that time, yet I’ve only seen a handful that were burned-out following accidents to the extent of the recent Tesla fires. I sensed something wrong, or at least counter-intuitive about the figures cited by Tesla.

The National Fire Protection Association (NFPA) lists highway vehicle fire data going back to 1980. Although the number of annual car fires has declined by over 60% in that period, there were still over 170,000 motor vehicle fires in 2012, resulting in 300 deaths, 800 injuries and $1.3 billion in property damage. That makes it a serious concern. However, in NFPA’s analysis of detailed data from 2003-7, fires resulting from collisions made up just 3% of the total. Various other factors caused the more numerous, non-collision fires, including mechanical and/or electrical failures, exposure to other fires, and a startling 8% of fires that were set intentionally. On that basis, the 172,000 fires-per-year figure doesn’t strike me as a very good basis for comparison to the Tesla fires.

Comparing Collision Data

From what I could determine, NHTSA measures vehicle fires on the basis of accidents, not population, and specifically by the number of incidents per 1,000 vehicle crashes. NHTSA’s 2011 “Traffic Safety Facts” report indicated a fire rate of 0.96 per 1,000 crashes overall and 3.1 per 1,000 fatal crashes. The 9,000 collision-related fires NHTSA found in 2011 are consistent with collisions’ 3% share in NFPA’s analysis. The rate of around 1 per 1,000 crashes also ties to the rate calculated by the Motor Vehicle Fire Research Institute from fire data from the 1970s to 2001.

This puts the Tesla fires in a somewhat different light. An apples-to-apples comparison between the recent accidents and gasoline cars wouldn’t be fires per 1,000 Teslas, but fires per 1,000 Tesla crashes. Focusing on collision-related fires, rather than all vehicle fires, makes sense because this was the situation in which all three Tesla fires occurred, while NFPA found collision-related fires to be more than 100 times likelier to result in fatalities than vehicle fires arising from malfunctions not involving crashes.

I couldn’t find overall accident data for the roughly 19,000 Teslas now on the road. However, if their incidence of crashes were comparable to the roughly 9 million per year for the rest of the 242 million vehicle US light-duty fleet, that would yield around 700 accidents per year. Three fires in 700 accidents, or four per 1,000 crashes, would be a multiple of the incidence for the conventional car fleet.

19,000 cars isn’t a very big statistical base, compared to over 240 million, and this is just a back-of-the-envelope calculation in the absence of more detailed accident data for Teslas, not to mention other electric vehicles. Nevertheless, in this context it seems more understandable that NHTSA might want to investigate this matter further.

Conclusions – Car Fires Matter More to Tesla than GM

The Tesla Model S is a beautiful car and an aspirational vehicle for a generation attuned to the sweet spot between technology and environmental concerns. Few new-car buyers would steer clear of a GM or Ford, let alone a Lexus or BMW, because of the risk that less than 0.1% of all US cars will be involved in a fire this year. However, even if it turns out to be true that EVs like the Model S catch on fire less frequently than gasoline cars, the latter aren’t trying to win over new converts, at least in this country.

Mr. Musk is working hard to get out in front of an issue that, as yesterday’s Wall St. Journal Heard on the Street column highlights, could –fairly or unfairly– alter investors’ perceptions of future sales that underpin Tesla’s market value. Even though I have no stake in this other than my sense that EVs of various types are likely to dominate the passenger car market in the long run, I wish him well in resolving this issue.

  1. By Joe Villanova on November 21, 2013 at 2:20 pm

    You’re not taking into account the design of the Tesla versus any gasoline-powered vehicle and the safety features that are unique to the electric car versus the standard safety features of all fossil fuel vehicles.

    • By Geoffrey Styles on November 22, 2013 at 9:25 am

      Say more about that? I understand the argument about the total energy stored in the batteries being less than in a gas tank, and the firewalls they’ve installed. However, none of this prevented the total loss of the vehicles in question. What did you have in mind?

      • By Glen McMillian on December 21, 2013 at 10:31 pm

        It looks as if the Model S has a possible problem with fire in the event of a hard crash but t it’s hard to say for sure.

        If my info is good, two of them burned after running over debris in the road that punctured the battery housing from below and the third one crashed hard traveling essentially sideways, taking the hard impact in the door area.

        The occupants of the ones that burned as a result of debris in the road were able to stop and exit the car safely.
        If the fire dept isn’t really close and quick, almost any car fire means a totaled or destroyed car.

        But even though there may be a higher risk of fire in a Model S, it seems to be almost a foregone conclusion that it is a far safer car, in the event of a major accident than just about any other car on the road due to the superb design of the crush zones , and other safety features, as evidenced by it’s over the top scores on the crash tests..

  2. By exdent11 on December 2, 2013 at 9:18 am

    You do not include mechanical and electric car fires in your comparison. Why not? Whether initiated in a collision or not , a fire is usually feed by gasoline or vapors of gasoline that result in destruction of the car and death or injury. An EV does not carry that burden. Your comparison seems spurious.

    • By Geoffrey Styles on December 3, 2013 at 1:40 pm

      As I indicated in the post, collision-related fires in gasoline cars are disproportionally hazardous vs non-collision fires, with the 3% of fires in the former category accounting for 58% of deaths in NFPA’s analysis. By contrast, the 72% of fires resulting from mechanical or electrical malfunctions accounted for just 11% of deaths. Add this to the fact that all of the Tesla fires were collision-related, and it makes a strong case for collisions as the right common denominator, or apples-to-apples comparison.


      Perhaps what’s bothering you here is that intuitively EVs seem like they should be inherently safer than gasoline cars. I had the same initial impression, and in the long run there’s every reason to think that should be true, as Kevin Bullis of MIT’s Technology Review spells out:
      However, in this case we have a particular EV that from the limited statistical evidence available appears to be catching on fire in collisions at a rate that is similar to, or possibly a multiple of, the rate for gasoline cars. NHTSA is entirely justified in looking into this further, and Tesla should welcome this, either to clear up any misperception that’s being created, or to identify specific design issues that could be improved to make the cars as safe as intuition suggests they should be.

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