OK so apart from the colour, can you spot anything else different about these two cars?

The answer isn't what you think.

Yep it's coconuts but before you think i've gone totally nuts let's go to an island called Bougainville in Papua New Guinea just north of Australia.

Life on Bougainville is a bit tough at the moment - everyone is struggling to get back to normal after a civil war where there was a lot fighting.

It's also hard on the island because they need to bring in a lot of stuff from other places for their day-to-day needs, like fuel, for example.

But the trouble is sometimes deliveries don't arrive and the pumps and the cars and trucks dry up.

So locals have turned to coconut oil.

The word coconut refers to the nut of the coconut palm tree - which can be found all over the tropics.

Nearly all parts of the tree are used for heaps of different things.

But what makes the cars run comes from this - copra - the white fleshy bit inside the coconut - which is the main source of coconut oil.

MATTHIUS HORNE, COCONUT FUEL MAKER: Here we got the raw material which is the copra - it goes into the primary crusherm it feeds through the secondary crusher and it then expels the oil which comes flowing right out of these gaps here.

This guy is the coconut king .. in a shed in the jungle he brews up the copra to make the oil.

MATTHIUS HORNE, COCONUT FUEL MAKER: And then right into the filter presses here which take take all the bits and pieces out of the oil and then into these holding tanks system here - and after two weeks time we can use it straight in our cars.

MATTHIUS HORNE, COCONUT FUEL MAKER: They sometimes refer to me as the mad german because how can you do that to your car filling it with coconut juice.

Mathius Horne is coconut crazy, but he's not crazy, he's actually making big business out of his coconut fuel.

He says coconuts are one thing Bougainville has stacks of, so coconut power makes good sense.

MATTHIUS HORNE, COCONUT FUEL MAKER: The coconut tree is a beautiful tree. If you run a car and it smells nice and it's environmentally friendly - and that's the good thing.

Now coconut oil can't be used in cars that use petrol, it can only be used in engines that run on diesel.

And coconut oil is actually cheaper than diesel so more and more people are turning to it.

It's used in cars, trucks, tractors - all sorts of engines, even boats.

But before you go trying out the idea in the family car, you might want to think again.

Pure coconut oil gets hard - and looks like this when the temperature drops below a certain point.

So for people in cooler places, your car just wouldn't work.

But that hasn't put off the coconut king, he's back in Bougainville working on ways of solving this problem, so people all over the world can use coconut oil to run their cars.

He reckons it's only a matter of time before the idea catches on.