DIESEL cars have become popular with business car drivers for their low company car tax rates and less frequent refuelling stops.

But with temperatures plummeting to below 18°C – and forecast -20°C in some parts of the UK – the very fuel that provides such extended range may well stop drivers in their tracks. Diesel fuel can wax over in extremely low temperatures, which could damage the fuel filter and cause a breakdown.

Neil Greig, head of policy and research from the Institute of Advanced Motorists (IAM), said: “Diesel waxing is the formation of crystals in the diesel which block the filter. If you drive a diesel vehicle, it pays to try and park in a garage or sheltered area, and try to not to leave your vehicle standing unused for too long.”

Oil Companies supply winter diesel fuel that can withstand temperatures down to -15°C from October to March – but the current temperatures are the worst for some 30 years.

“If you can’t park in a garage, do ensure that the engine bay of the car is parked downwind, so that the wind hits the back of the vehicle first,” added Mr Greig. “After starting the engine, let it idle for 10 minutes before driving off, as this will let the heat from the engine warm the filter and pipes.”

Lorries with exposed fuel tanks and fuel pipes are most at risk of diesel waxing but cars and vans can also be affected if it’s cold enough.

Water in diesel fuel tanks and filters can also freeze. Mr Greig advised: “Keep the fuel tank full and, if possible, fill it before arriving at home as this will prevent the build up of condensation on the inside walls of the tank, helping prevent water building up in the bottom of the tank.”