A nearly nine-month investigation by U.S. auto safety regulators has found 27 reports of engine fires in tiny Smart Fortwo cars, including one that caused an injury.
The finding of the unusually high number of fires prompted the National Highway Traffic Safety Administration to upgrade its probe from a preliminary investigation to an engineering analysis. That's the last step before issuing a recall but it may not necessarily result in one.
Mercedes says it's cooperating with the investigation but declined further comment.
In documents posted Wednesday, NHTSA said one person reported smoke inhalation in a fire, but the extent of that person's injuries was not available.
The agency began investigating nearly 43,000 Smart cars made by Mercedes in December. The cars are from the 2008 and 2009 model years.
NHTSA said in documents that Mercedes investigated only two of the fires but could not find a cause. The agency said 19 of the fires happened since January of 2015, a sign that the problem is becoming more frequent as the vehicles age.
Investigators analyzed insurance data and found the 2008 model year cars had significantly higher fire claims than comparable vehicles. Data from the Highway Loss Data Institute, which represents insurers who cover 80 percent of the U.S. market, showed a higher claim rate than similar vehicles. It also showed a sharp increase in claims in 2015, the agency wrote.
NHTSA said in documents that it will "continue to investigate the high frequency and increasing trend of non-crash engine compartment fire incidents in the subject vehicles."
The Smart brand is getting rid of its gas-powered versions in the U.S. and Canada and will sell only electric cars after the 2017 model year.