This issue can be caused by a dirty or greasy track, dirty tires, or a defective car. Please note it is not unusual for the cars to go off the track during game play.
Dirty or Greasy track:
Clean the track using the instructions provided here.
We also recommend cleaning the rear tires using the tire cleaning pad included in the Anki DRIVE starter kit at the same time you clean the track. If the tire cleaning pad is dirty, you can clean if using the instructions provided here.
First check the rear axle for any debris. Pet hair or long hairs can get wrapped around the rear axle and cause issues. Try to clean out as much of the debris as possible using a tweezer or a pin. If this is not possible or if there are no debris, then please contact us for a replacement car.