So we've seen cars powered by burger grease, orange juice, hemp and something called Jatropha Curcas seeds. Nope, still don't know what they are.
But what about rotting apples? In a move as selfless as it is eco-friendly, Somerset farmer Henry Hobson has converted his Jaguar XJ6 to run off methane produced from the decomposing fruit in his orchard.
The science is simple enough: Hobson fills two underground tanks with apples from his 10,000-tree orchard, and adds a soupcon of bacteria from cows' intestines (yes, seriously) to help the rotting along.
The gas emitted from the decomposition is filtered through water to remove the sulphur and carbon dioxide, leaving Hobson with lots of lovely pure methane. And lots of lovely cheap fuel.
Hobson reckons that - discounting the £3,000 it cost to convert his Jag - he saves more than two grand every year on fuel costs. And as an added bonus, the big ol' XJ6 is putting out about 10 per cent more power at very similar fuel economy to before.
So is apple-power the future? Hobson maintains that methane is 10 times more efficient to produce than bio-diesel. And, as well as presumably filling the air with the sweet smell of home-brew, his fuel has the advantage of keeping the doctor well away.
Now, if only we could harness all that methane that our cows produce. Volunteers, anyone?