Not exactly an issue, but when driving cars off-road (the sandy paths) you should hear a lot of that sound when gravel and debris hit the bottom side if the car.

Driving on grass there may be a different kind of sound. Branches from trees may brush across the bottom side of the car and you'd hear some sounds once and a while.

On-road there may still be debris lying on the street and you may hear some gravel hitting sound once and a while.