So what happens when you give a designer a truly blank sheet of paper? No rules, son, do your worst. This is what happens. This is the Honda Racer, a retro-F1-racer-meets-Top-Fuel-dragster masterpiece, created by Honda's senior American designer Guillermo Gonzalez. If it doesn't give you a warm, happy buzz of excitement, you need to book yourself a trip to Disneyland to rediscover your inner child. And, OK, we'll admit it now: it's not real. Never will be. Never could be.

Sorry. It's a Hot Wheels car, designed to celebrate the 40th birthday of the American company, famous for building those collectible die-cast cars. But, just for a minute, suspend your disbelief. Ignore the fact that it's a fantasy - the equivalent of the doe-eyed, massive-breasted Manga creation of a teenage bedroom scribbler - and just enjoy it.

See that massive mid-mounted engine under the red valve covers? That's a 20-litre V10, that is. Yes, two litres per cylinder. Imagine the noise. Look at that tangled, twisted mass of exhausts. Look at the retro-Japanese paint job. Imagine what an improvement that'd make to Mr Button's weekend runabout...

But no, the only driving this car will be doing is via the hand of a giant child. Well, at least in proportion to the car. Talking of huge, over four billion Hot Wheels cars have been built since 1968 and, on average, each child in the USA today owns 15 Hot Wheels cars. Truly massive.

So when Hot Wheels approached Honda and asked it to come up with cars as part of its Design Challenge - the first time that Hot Wheels cars have been designed out-of-house - it's no surprise they wanted to do something special.

"It was so liberating to be given a blank sheet of paper and told to go wild," says Gonzalez. "Our only aim was to do something that fitted in with Hot Wheels' identity and with Honda's image. And looked cool."

So where do you start? "We looked at doing jets, motorcycles, even lawnmowers," says Gonzalez, "but the thing we kept coming back to was Honda's F1 racing in the Sixties, especially John Surtee's Hondola [the Lola-underpinned 1967 F1 car] which won its first-ever race. Its a bit of a legend round here."

Hence the red-on-white livery, the intricate, exposed exhaust system, the distinctive, snoutish air inlets at the front. Google 'Honda RA300', and you'll see the family resemblance.

But is it pure fantasy, nothing more? "Everything has been completely exaggerated," admits Gonzalez. "But the car still had to 'work' - I used bits of Honda engine design from the last few years, and the overall shape had to make aerodynamic sense. I guess that's why it appeals to grown-ups as well as six-year-olds. It's still grounded in some sort of reality.

And of course, Hot Wheels had to be able to build the thing."

That's the best bit: you'll be able to buy the Honda Racer. Not in full 20-litre engine form, admittedly, but a 1/64 scale Honda Racer? For a couple of quid from your local supermarket? Surely you're not too grown-up to resist?

"I think when people see a production car, they look at it with a critical eye, as if they're imagining buying it," says Gonzalez. "But when they look at something that is, in essence, a toy, they can be more childish about it and enjoy it."

So do it. Forget about NCAP ratings and mpgs and, y'know, the real world for a minute. Get yourself a tiny Honda Racer, and remember why cars are great again.

And who knows? If enough of us do, it might just convince Honda to build it for real. It might.