So what sort of cars run best on biofuels?
Well, in principle any diesel will run on biodiesel or SVO (straight vegetable oil). Most people run older, indirect injection engines, and the best of the lot are the old Mercedes diesels.
One thing you need to take into account if you are running biodiesel is that it is a more aggressive solvent than regular diesel and can potentially chew out the rubber seals in your fuel injection pump. This is not a major problem, as you can get it rebuilt with Viton seals, which solves the problem.
This is not cheap, but as a one off expense it quickly pays for itself with the cost of diesel these days.
Can you run a modern, common-rail engine on biodiesel? I think the answer is yes, but there are lots of people that say no. I think this is for a couple of reasons. Firstly, the manufacturers warn against it, mostly because I think they don’t want people putting fuel into their cars that they made in their backyard, and then coming to them for a warranty claim.
The second reason I think is that a lot of people that make BD in their backyard don’t know what they are doing, and can make fuel that can damage an engine. The issue with common rail engines is the higher injection pressure, and BD is more viscous than regular diesel, so this is another cause of concern.
But for 10 people who say you can’t run a certain car on BD, all you need is one person who says they can, and you have your answer. And I have yet to find a car that someone, somewhere, is not running on biodiesel