That stalling sound in the opening race of Cars is the first-ever sputtering-out of imagination and immersion from Pixar, the studio that pioneered computer animation with Toy Story.

It’s all hammer-cut editing, loud Sheryl Crow on the soundtrack, whizzing cars, zooms, zips and, as lead car Lightning McQueen likes to say, plenty of “bee-urr, bee-urr” and “poo-chi-cowww.”

Those are the cocky racecar’s catchphrase sounds for revved engines and downshifts, but it’s a dull drone of excess. Cars tosses out glitz the way Rip Taylor does confetti, and it’s a jarringly superficial, showy start that Pixar has not had to rely on for any of its previous productions.

Though never mentioned specifically by name, this is NASCAR, and only because it’s animated and populated by self-driven cars does this opening differ from Fox’s pre-race bumper spots. Pixar always has been great at creating worlds; mimicking the real one doesn’t appear to be a strong suit.

This bit also is meant to excite, not contrast with the fine movie Cars becomes after its first hour — a parable about true friendship’s give and take, and appreciation of life’s smaller pleasures.

At least the technical innovation still is there, as Cars rivals Finding Nemo‘s uncanny realism with detailed dust and expansive desert vistas.

But cars lack the expressive capabilities of fish, bugs, toys and monsters. Without inspired vocal performances by Owen Wilson, Bonnie Hunt, Paul Newman, Tony Shalhoub and Larry the Cable Guy (a perfect voice choice), those lazy Willy ’n Ethel-style eyes wouldn’t make for much.

Lightning (Wilson) is a rookie racecar phenom, competing with retiring vet The King (Richard Petty) and dirty-driving Chick Hicks (Michael Keaton) for the prestigious Piston Cup. The red rocket has the win — and the big-ticket sponsorship that comes with it — in hand until he avoids pit-crew advice and his tires blow. With a humorous Michael Jordan reference, it’s a three-way tie.

Easily the biggest jerk Pixar’s ever positioned as its hero, Lightning forces his sleepy tractor-trailer Mack (John Ratzenberger) to drive all night to California so he can have a long prep for a cup-deciding race. When boom cars with ground effects ironically send Mack to sleep, Lightning falls out the back, dropped on a dark, desert highway as a racecar with no headlights. Panicked, he demolishes the main drag in Radiator Springs, a tiny burg on Route 66 that snails would find slow.

Punished with re-paving the road, Lightning becomes stuck in Radiator Springs while fixing to get at the race. But he gradually befriends a hayseed truck named Mater (as in Tow, voiced by Larry the Cable Guy), falls for a former big-city Porsche named Sally Carrera (Hunt), learns a few tricks from Doc (Newman), a ’51 Hudson Hornet with a few secrets, and learns of the town’s pride — and heartbreak — of being along a road where time-saving drivers no longer go for a good time.

Some car puns are funny (all of the bugs are Volkswagens and Chick is sponsored by Hostile Takeover Bank), but ambling gags in Radiator Springs repeat ad nauseum. Only Mater and the proprietors of a tire shop — race-loving Italians Luigi and Guido (Shalhoub and Pixar animator Guido Quaroni) — spark with their silliness. And Newman’s gravelly growl is an entrancing addition to the movie — full of wisdom, stubbornness and, surprisingly, a lack of self-esteem.

It’s when the movie reveals more about Doc that it hits a stride of memorable moments — a sepia-toned montage about interstate intrusion, a sweet neon-lit bop-and-cruise down the streets of Radiator Springs to the tune of “Sh-Boom,” the final race that’s a classically clap-worthy, Pixar package of character-driven action. (How marginalized Guido makes his presence felt in pit row is triumphant and hilarious.)

The problem is that this rubber doesn’t hit the road until the movie is more than halfway over. At 116 minutes, it drives under a caution flag one-third of the time, and both kids and adults will restlessly await the rally of this warm-hearted conclusion. It’s no lemon, but Cars is the first Pixar vehicle to try and cover up its rust spots with fancy pinstripes.