Biodiesel: five questions and answers

1. What is biodiesel?

The fuel generally known as 'biodiesel' is actually rape methyl ester (RME), which is produced by the chemical treatment of rapeseed oil in a process called transesterification. This improves its fluidity and ignitability, thus making rape methyl ester very similar to conventional diesel fuel in its essential properties.

2. Can I run my car on biodiesel?

Only cars explicitly labelled by the manufacturer as suitable for biodiesel should be run on it. Otherwise, according to the German automobile club ADAC, there is a possibility of damage being caused, e.g. to the fuel-injection pump. It will also mean that you cannot claim under warranty or guarantee and that the manufacturer is unlikely to offer any compensatory gesture of goodwill. So before you fill up, do check your user manual to ensure your car is biodiesel compatible. If you have any doubts, it is safer to ask the manufacturer. In the current 'new car programme' (Euro 4 standard on exhaust gases), only the VW Golf V and Skoda Octavia II are approved for biodiesel – but only if they have been ordered with the special biodiesel option at an additional charge. Audi, BMW, Mercedes, Peugeot, Seat, Skoda, Volvo and VW have given biodiesel approval to some older models.