The lawsuit, filed in a federal court for the southern district of Florida, says Ford marketed the muscle car as a”track ready,” in an effort to entice potential race-enthusiast customers. But the some of the vehicles didn’t live up to the claims and were unusable, according to the lawsuit.

After 15 minutes or less on a race track, the transmission and rear differential on the car would overheat, the lawsuit claims, causing it to drastically reduce speed and power—known in the industry as “limp mode.” This sudden loss of speed puts occupants at risk, the lawsuit alleges.

“Ford is committed to providing our customers with top-quality vehicles. However, we do not comment on pending litigation,” company spokesman Bradley Carroll wrote in an emailed statement.

For more on Ford: What’s New In the 2018 Ford Mustang

The lawsuit claims that Ford chose to equip the Shelby GT350 base and technology package models with defective transmissions and rear differentials that make the power train systems in these specific cars unable withstand the demands of race track driving.

An estimated 3,991 Shelby 350GTs could be affected by the defect.

The lawsuit goes further claims Ford later inadvertently admitted the defect by advising owners to buy rear differential and transmission coolers for their 2016 model year cars—at their own expense—in order to actually make them ready for a race track.

The four plaintiffs, who said they paid about $57,000 for the track ready version of the 350GT, have demanded a jury trial. The lawsuit was filed on behalf of the plaintiffs by Hagens Berman Sobol Shapiro, a law firm based in Seattle and Grossman Roth Yaffa Cohen in Florida.