The National Highway Traffic Safety Administration is now investigating the potential for engine fires in certain Smart ForTwo city cars.
Approximately 43,000 cars built during 2008 and 2009 are affected.
An investigation was started after the NHTSA received eight complaints reporting incidents of engine-compartment fires in cars from these two model years.
All of the eight reported incidents from Smart ForTwo owners involved "severe fires that rapidly engulfed the vehicles," according to a summary on the NHTSA website.
In six of those cases, drivers reported seeing smoke or a check-engine light, or hearing unusual noises, before pulling over and finding a fire in the engine compartment.
The other two fires were not detected until after the cars were stopped, according to the NHTSA, which opened its investigation December 16.
Five of the reported incidents occurred in 2015, and the three most recent all occurred after October 2016, the agency said.
Vehicles in the reported incidents had between 29,000 and 86,000 miles on their odometers; the average for the group was 54,000 miles.
No injuries have been reported so far, and Smart parent company Daimler says it is not aware of any.
The NHTSA probe constitutes a "Preliminary Evaluation" to assess the "cause, scope, and frequency" of the fires.
No recall has been issued so far, although the investigation may lead to that outcome.
The NHTSA may request additional information from Smart parent company Daimler before determining whether a recall is necessary.
The Smart ForTwo models involved in the NHTSA probe are among the earliest examples of the car sold in the U.S.
Smart began importing the ForTwo here in calendar year 2008, after selling the car in other markets for several years.
A redesigned version of the ForTwo coupe was introduced to the U.S. as a 2016 model, followed by an updated convertible for the 2017 model year.
ForTwo owners with concerns regarding the NHTSA engine-fire probe can contact customer service at 800-367-6372.