Driving on rough roads, such as those made of gravel or dirt, will affect your gas mileage by as much as 30 percent. If there is an alternative route that you can take, you should consider taking it if it isn’t going to add too many miles onto your trip.
The wear and tear to a vehicle that is being driven over rough gravel road can damage the underside of your vehicle, causing damage that you’re not aware of for some time to come. This damage, even if minimal, could be a factor towards increasing your gas costs and fuel inefficiency.