- 3 updates
It's a way of saving money that can prove very expensive indeed. Buying fuel at illegal filling stations, where duty hasn't been paid - you're buying a mixture that should never be put into a car engine.
If you're caught, your car could be seized by the taxman. If you're not, the damage to your engine could leave you rueing the day you stopped at a so-called "huckster" filling station.
Tom Sheldrick reports.
Welsh fuel retailers say their trade is being affected by competition from illegal filling stations.
Customs officers have raided two makeshift stations - in Caerphilly and Newbridge - in the last few months.
They've found thousands of litres of red diesel mixed with kerosene and sold cheaply as white diesel.
"Fuel prices have been doing up, and so if you can't buy the fuel you want, at the price you want, there is this alternative to try and resort to illegal tactics" says Brian Madderson, from the Petrol Retailers' Association.
HM Revenue and Customs (HMRC) has seized 17 vehicles and contaminated fuel in a raid on a makeshift filling station near Newbridge, Gwent.
Officers removed 4,750 litres of a red diesel and kerosene mix, along with with storage tanks and piping.
The vehicles were returned after a penalty was paid.
“Cheap diesel might seem like a bargain, but stretched fuel is not" says Stuart Fenton, from HMRC’s South West and Wales Road Fuel Testing Unit.
"Kerosene is not designed as a fuel for the modern car engine. It makes diesel more combustible, and prolonged use would undoubtedly damage the engine of any vehicle."
A spokesperson said a man has been questioned, and the investigation continues.