Ask an expert

Why has the cost of Diesel fuel gone up dis-proportionately to the cost of petrol over the last few years?
I have a diesel car but now find that according to the AA running cost calc's
a petrol fuelled MV is cheaper to run than a diesel engined one!!

Diesel costs more to produce than petrol, particularly the high quality low sulphur diesel mandated in many countries like ours. But the main reason diesel prices have risen is because of growing demand to to economic growth, especially in China and India. Diesel is the fuel is commerce, essential for land and sea freight, public transport, agricultural machinery etc. By comparison, global petrol demand is more stable as it is generally only used by motorists so less subject to fluctuations in demand although of course as diesel demand rises so does oil demand which effects prices for both. Over time, expect the price cap between diesel and petrol to narrow, for private diesel motorists you are competing with consumers who cannot switch to a petrol-powered (or hybrid) vehicles.