This issue is most often cause by the following reasons:
Misaligned rear tire
The rear tires on the Anki DRIVE cars can occasionally come off or become misaligned from the wheel and cause the car to behave abnormally.
Damaged rear axle gears
The gears inside the car can become damaged. Sometimes you can detect this by using your fingers to slowly spin each of the rear wheel. It helps to compare it to a car that does not have this issue. Typically when the gears are damaged there will be more drag or rough feel when moving the wheels. If this is the cause of your issue, please contact Anki Customer Care.