Speed Racer (PG)

The Wachowski Brothers have been quiet since the two vapid, overblown Matrix sequels five years ago, and some of us may have preferred it that way. Now they're back, I'm afraid, and with a movie of such garishness and impenetrability as to test the stoicism of any audience member older than 14.

Imagine being locked in a video arcade with wall-to-wall screens all going loudly and simultaneously berserk. Most computerised action-movies nowadays look as if they've been designed exclusively for people with attention deficit disorder. Speed Racer looks as if it's been designed by people with attention deficit disorder.

Whatever else The Matrix did, it pushed the movie of universe-as-facsimile as far as it could go. Or so we thought. This time out the Wachowskis have dispensed with physical background altogether, substituting it with digitised sets of hyper-real colours and toytown visuals. Within this virtual artifice some quite respectable actors are obliged to take their chances. The story, of course, presents no such innovation: a young racing driver must choose between profit or integrity as he challenges for the Grand Prix. The name of our hero? Speed Racer. The writers simply couldn't come up with a name that wasn't also his job. It's like calling a soldier hero Sharp Shooter, or a football one Centre Forward.

Speed, played by Emile Hirsch, lives with his proud parents (John Goodman, Susan Sarandon) – as so many racing drivers do – and has a chaste relationship with his girlfriend Trixie (Christina Ricci). When he's courted by corporate giant Royalton Industries, he takes the whole Racer family, including a pesky younger brother and his pet chimp, to meet and greet smooth owner Royalton himself (Roger Allam), but one look at the latter's custard-yellow jacket and purple shirt puts us on alert that he's a capitalist megalomaniac, not to say a very bad dresser.

When Speed politely declines the big bucks in favour of his dad's own garage team, the stage is set for a fight between the sharks of big business and the minnows of mom-and-pop independence. Baring his teeth unpleasantly, Royalton crows over the prospect of finishing off Speed's career before it has barely begun, a triumph that will signify "the unassailable might of money".

The moral rings rather hollow, however, when you know that Warner Bros – no strangers to the might of money – will already be merchandising the life out of this movie.

This cartoonish sense of conflict, while hardly credible, isn't actually unbearable. Where the movie falls apart is in its frenetic racing sequences, which not only defy the laws of physics but flout the limits of tolerance. The camera noses up to the drivers in their vehicles, close enough to count the beads of sweat on their faces. Once out on the track, however, the cars simply careen about the place like the weightless pixelated things they are.

In the high-speed wrecks only one driver is seen to die – that's Rex, Speed's idolised older brother – and doubt is cast even on his dusty death. The rest of the time the crashed cars merely spin over and the drivers dissolve into foam balls. Everything goes by in such a blur as to make it utterly meaningless. It's like Wacky Races, only twice as fast and without the comedy – you could call it Wachowski Races. There's even a Dick Dastardly figure who runs our hero off a mountain road and cackles madly as he drives away. I didn't spot Muttley, however. Perhaps he was behind the camera. In any case, Speed isn't going to be bested: why, isn't that him driving straight back up a cliff-face? No telling how he does this – Speed is the hero, and as far as his creators are concerned, he can do anything.

With little else for the eye to feed on you are left to watch the actors as they pretend to get worked up. I was briefly fascinated by Spritle, the tween Racer brother played by Paulie Litt – a smart agent would have advised him to change that name (say it out loud), though the kid can do nothing about having a face like a little old man's. Ricci has the right saucer eyes for this hybrid – it's based on Tatsuo Yoshida's animated series – though her features are so small that she's beginning to resemble a very good-looking cartoon turtle.

If the movie had been smarter it might have had some Best in Show-style fun in the commentary box, where the choice of actors tends to the bizarre. Richard Roundtree, once the superfly private eye Shaft, is paired with British TV comic Ben Miles, though neither can beat Ramon Tikaram – Ferdy from This Life – for sheer novelty value. It chimes with the random design of the movie in general.

The least pardonable aspect of the whole enterprise is its length. Speed Racer whines on for two hours and 15 minutes, by which time surely even the most impressionable 12-year-old will be dreaming of a quick return to Grand Theft Auto IV. Indeed, one wonders if the younger generation won't find Speed Racer's format just a little passé: don't their thumbs start twitching during these non-interactive digimations?