Grease is the word!

They've driven to Athens all the way from London - nothing too unusual about that - except these motors are running on reused cooking oil.

Environmental enthusiasts - keen to promote the virtues of cheap and eco-friendly bio-fuels - have been taking part in a 4,000 kilometre rally across Europe.

It sounds a little far-fetched but apparently it's very simple to convert your engine.

SOUNDBITE: Ben Mayo, Fuel Convertor System Designer saying (English):

"This is a converted engine, it looks much the same as a regular engine. There's a few minor adjustments, this is the heat exchanger - that is what heats the fuel up and make it nice and hot and ready for injection into the engine."

The ten day mission involved some pretty good bargaining skills - the team managed to obtain used cooking oils from restaurant, cafes and fast-food joints along the way.

SOUNDBITE:Andy Pag, Organiser of Grease to Greece saying (English):

"We have been surprised at how easy it has been. The problem has been actually finding places that have oil and arriving at the right moment before its been collected or taken away. But actually when people have had oil they have been really really willing to give it and let us have it. I mean it's a waste product for them so we are taking away their rubbish really."

It isn't the first time that organiser Andy Pag has taken part in such folly - last year he drove to Mali in western Africa in a truck powered by waste chocolate.

SOUNDBITE:Andy Pag, Organiser of Grease to Greece saying (English):

"When I first put vegetable oil in the car I was really worried (I thought) Oh my god is it going to work? Is it going to blow the car up? I have now done over I think 6000 miles on vegetable oil and I have had absolutely no ill effects at all."

So, what next for this experienced eco-traveller you might ask? Well, he's planning a globe-trotting adventure using aviation fuel made from recycled plastic bags.

And if he happens to persuade a few people to convert to cooking oil then his mission will be all the more successful.