The price of diesel in rural filling stations is, on average, 4p more than in urban areas, a new survey shows.
Cars are becoming an "unaffordable necessity" for many living in rural communities, said the Countryside Alliance, which conducted the survey.
The costliest diesel - at 146.9p a litre - was in Purbeck in Dorset and Ryedale in North Yorkshire.
In contrast, diesel in Birmingham and in Dartford in south east London was "only" 139.7p a litre.
Overall, the alliance found that diesel in rural areas averaged 144p a litre, while in urban areas the average was 140p.
Countryside Alliance executive chairman Barney White-Spunner said: "Not only do people living in rural areas have to drive further to go to work, further to access essential services like schools, doctors and the supermarket, but they have to pay a lot more for their diesel to do so.
"The cost of fuel is a major concern for everyone who lives in the countryside, and cars are fast becoming an unaffordable necessity for many rural families. We urge the Chancellor to help the rural economy get back on its feet and to cut fuel duty in his forthcoming Budget."
The alliance survey follows findings earlier this week that UK motorists pay more in fuel tax than any other drivers in Europe.
And a report by the Centre for Economics and Business Research (CEBR) has said that cutting fuel duty would create thousands of new jobs and could be done at no loss to the Treasury.
Campaign group FairFuelUK met Treasury Minister Chloe Smith this week, armed with the initial findings of the CEBR report.