Now celebrating 20 years of creating animation history, Pixar - the makers of 'Toy Story'; its follow-up; 'A Bug's Life'; 'Monsters, Inc'; 'Finding Nemo' and 'The Incredibles' - have returned with 'Cars', a film about a human-free world that some expected to (top) trump all their previous movies, but instead often veers over the central line between watchable and disappointing.

Over-confident rookie racecar Lightning McQueen (Wilson) almost wins the legendary Piston Cup on his debut, but his know-it-all attitude means that he has to settle for a three-way tie with soon-to-retire great The King (Petty) and Chick Hicks (Keaton), another young pretender like McQueen whose ego also deserves its own trailer.

To decide the winner, the Piston Cup organisers arrange a race in California the following week. McQueen, having lost his pit team due to his mouth, must find his way across the US with big rig transporter Mack (Ratzenberger) the sole remaining member of his crew.

But McQueen's refusal to let Mack stop for a rest costs him dear. Along the way Mack is hassled by some hot rods and a series of events leaves McQueen stuck on the roadside while Mack carries on to California blissfully unaware that his cargo is missing.

McQueen ends up stranded in the bypassed town of Radiator Springs, where he incurs the wrath of local judge, garage owner, classic car and wise old head Doc Hudson (Newman), who sentences him to community service and orders him to repair the town's old road. Will McQueen devise his own great escape, or will he slowly learn that somethings in life mean more than winning?

While this could have been an animation classic, 'Cars' trundles along far too often to elevate it to the pantheon alongside 'Toy Story', 'Monsters, Inc' and 'Finding Nemo'. You can't fault the characterisation from the stars and the gorgeous animation would make even the most bicycle-championing eco-warrior get all dreamy-eyed looking at the cars - the problem is the script.

'Cars' starts with a very watchable race but when the story moves to Radiator Springs directors Lasseter and Ranft slow the pace down so much that at times it feels like the film is stuck on a roundabout for the best part of an hour. A bit of tractor pushing (think cow tipping with wheels) and scene-stealing goofy tow truck Mater (Carlin) aside, there's not enough excitement in the middle to keep the audience - young and old - as interested as they should be. And while 'Cars'' message about progress destroying small towns, the importance of community and people needing other people is an important one, it could have been made in a zippier way.

Still one for fans to see but, unlike its predecessors, not a film that warrants repeated viewing.

Harry Guerin