Sales of the Hyundai Elantra have been moving at a brisk pace, mostly from consumers trying to save on gas.
But Monday the National Highway Traffic Safety Administration announced they have launched an investigation after receiving reports of the car's engine stalling.
One Elantra stalled on the highway and caused a three-car crash that injured one person.
A Hyundai spokesperson said it is cooperating with the investigation and said it is too early to draw any conclusions.
The Elantra gets 33 miles per gallon on the highway and sales have grown 50 percent since June.