Avoid Driving On Rough Roads
When possible try to avoid driving on rough road surfaces like gravel or heavy dirt. Driving on these kinds of surfaces can reduce your fuel consumption by up to 30%. Even if a route on smooth tarmac is slightly longer the reduction in friction will mean a much better MPG so it is worth going the tarmac way.
Very rough surfaces can also damage your paintwork and if hilly you may even damage the underside of your car. Both these will cost money to repair so it's another reason to try and avoid rough roads.
Some times it may be unavoidable and you have to go down certain roads, if possible try to go as slow as you can to avoid damaging your paintwork and underside.
Image credit: sxc / taz 2005