James on: the future of flying cars

Somewhere deep in the vaults of the TopGear archive is a hideous box that should never, ever be opened. It contains a handful of films that we've made, but never, ever shown, and the stuff in there is known as the ‘Too Rubbish to Show' collection.

I hope this box is never uncovered. I hope it is buried as completely as that crate at the end of Raiders of the Lost Ark, because, as with the Ark of the Covenant, opening it would be too dangerous, especially for us.

In there is my and Hammond's Unfunny Bus film, the existence of which torments me nightly. "Show it! Show it!" I hear you cry, but we won't, because it is genuinely and catastrophically unfunny. And not even in a funny way.

There's Jeremy's test of an American sports car - a Pontiac, I think - and something about a bullet-proof Fiat. There's some unfinished guff with me driving a rally car, and other things I have mercifully forgotten about. I hope there's a freak fire. If there is, it won't actually be that freaky, because you can be pretty sure we will have started it.

There are unused ideas, too; many of them rejected on logistical grounds, some because they were just too expensive, and some because even we could see that they just weren't funny. And then there is the thick file relating to my flying-car project.

This was going to be good: so good it was intended as a one-hour documentary by itself. It would be based on either a Caterham 7 or an Ariel Atom, with detachable flying surfaces and a prop driven by the engine. I would be able to fly swiftly between race circuits, take the wings off, enjoy [sic] a track day, rebuild my aeroplane, and fly on.

It was all quite well thought out, with the help of some people who formerly worked for the likes of Airbus and BAE Systems. There were detailed drawings, weight and balance calculations, specifications for the propeller - everything. It would almost certainly have worked. But it was monumentally costly and burdened with tiresome legislative considerations, so eventually we abandoned it.

Good. Because, now I've thought about it, the flying car is, and always has been, a stupid idea. It's not even a new idea. As soon as the aeroplane was invented, one of its pioneers, Glenn Curtiss, started trying to mate it with the automobile to form what he called his Autoplane, and with resounding failure.

Later efforts worked rather better, and, in fact, I've flown one, the post-war Taylor Aerocar. I wouldn't have flown it if I'd seen the wings were attached with elaborate paperclips, but, by the time I realised this, we were already at 2,000 feet.

As an aeroplane, it was actually pretty good, but then, it would be, because an aeroplane is what it was, and one designed in 1949, by which time aeroplanes were quite well understood. As a car - that is, with the wings, tail and propeller removed - it was diabolical. Worse than the Beetle, to be honest, and not helped by the requirement to drag all the unwanted aeroplaney bits behind you on a trailer.

Aeroplanes require a runway for taking off and landing, and, in crowded Britain, that means an airfield, where arriving pilots can generally book a taxi. Booking a taxi is easier than dismantling an aeroplane, which is why the streets of our cities are not filled with wingless Cessnas trundling about.

Well, you might be thinking, what about something that can take off and land vertically? A helicopter, for example? Nice idea, but you can't land a bacon-slicer in a built-up area because too many people would end up with no head. So you're back to the airfield ringing Ace Minicabs.

The only feasible way that a flying car could work is if it took the form of something like Paul Moller's Skycar, powered by pivoting and enclosed ducted fans or small turbines. That way, it could take off and land vertically without killing everyone, and, by the clever use of an aerodynamic lifting body, it could be largely free of pesky wings and would fit on normal roads. It could be alternately flown and driven, without recourse to spanners.

But this is where the idea falls down completely. If your car can fly, why would you drive it? No one is going to drive around until the traffic gets too bad and then take off out of frustration. If your car flies, you will fly everywhere.

So, in fact, the flying car is a completely paradoxical idea. These things are generally either cars or aircraft. And if they're both, they're actually just aircraft.