The Little Engine That Could, the plucky little dynamo who beats the odds by believing in herself, gets a radical remake in “Turbo,” the story of a high-revving snail who enters the Indianapolis 500.

This riff on the classic tale delivers the upbeat message that with the right attitude (and some magic) even a mollusk can overcome obstacles physical, environmental and emotional to land in the winner’s circle.

The hyperactive new DreamWorks film is a reminder that Pixar, once shorthand for animation excellence, has been losing ground. DreamWorks (“Madagascar,” “How to Train Your Dragon,” “Kung-Fu Panda” and “The Croods”) can’t top the polished virtuosity of the Disney subsidiary’s finest work, but it has consistently outshined Pixar’s less inspired releases. This ode to white-line fever runs rings around “Cars” and “Cars 2.”

By day, Theo the snail (Ryan Reynolds) works a spirit-sapping job at “the Plant.” That would be the tomato plant in a Los Angeles tract home’s garden patch. He’s fussed over by his protective, persnickety brother Chet (Paul Giamatti). He’s regularly slimed by overripe tomatoes.

He’s bored up to his eyestalks by the sluggish pace. “The sooner you accept the dull, miserable nature of your existence, the happier you’ll be,” Chet counsels.

After dark, Theo’s imagination cranks into overdrive. Watching old car-racing tapes on the humans’ TV, he dreams of becoming Turbo, the planet’s fastest snail. Inspired by the positive-thinking creed of his human hero, champion racer Guy Gagne (Bill Hader, with a French-Canadian accent thicker than maple syrup), Turbo dreams of glory at the Indy 500. As Guy says, “No dream is too big and no dreamer too small.”

When Turbo is sucked into a street racer’s carburetor, the nitrous oxide that supercharges the engine amps up our little hero’s horsepower. Suddenly he’s faster than a flash, and instead of slime trails he’s leaving sizzling exhaust contrails of neon-blue light in his path. Escar-go.

His potential catches the eye of tubby taco-truck driver Tito (Michael Peña), who tries to use his remarkable abilities to draw tourists to the rundown strip mall that is his home base. His more grounded brother Angelo (Luis Guzman) is as much a buzz kill as Chet, telling Tito to ditch his impractical schemes and concentrate on taco transportation. But with the help of a gaggle of sassy snails (a stupendous supporting cast led by Samuel L. Jackson, Snoop Dogg and Maya Rudolph) and mall shopkeepers (Michelle Rodriguez, Richard Jenkins and a priceless Ken Jeong), the go-go gastropod is soon Indiana-bound.

Thanks to what fans of animal-themed sports movies call the “Air Bud Loophole” (the rules don’t say an animal can’t play) Turbo is soon revving up at the starting line. Guy proves much less sporting in person than he appears on TV, however, and the competitors’ uncontrolled spinouts and treacherous rubber patches from shredded tires make for a thundering, dangerous race. In the end, both Guy and Turbo are locked in a grueling battle of millimeters.

Oddly for a racing film, “Turbo” is not as fast on its feet as one would wish. Does it make sense to say that the jokes are fine but there are too many of them? It’s an SUV of a film, awash with chrome details, spinny wheels and irrational running lights. There’s a ton of filigree in the story line, repetitive plotting and characters enough to keep us in first gear when we should be sprinting ahead. And the moral of the piece gets a little blurry when our underdog hero triumphs because of his Lance Armstrong-like performance enhancers. Mom and Dad, prepare for a teachable moment explaining that.

Still, there’s plenty of good stuff under the hood. The script has a nice sense of sports savvy (Robert Siegel, writer of “The Wrestler” and “Big Fan,” take a bow), and the ace voice cast makes a dozen colorful characters come alive.

The animation has a luminous look (cinematographer Wally “Dark Knight” Pfister consulted) and Henry Jackman’s score is addictively bouncy. The multicultural vibe is enjoyable and there’s a mildly risqué gag concerning Michelle Rodriguez’s grease-monkey auto shop owner, and the less said about it the better. So, some stitches show.

“Turbo” isn’t a perfect cartoon, but it’s so likable that, like its humble hero, you have to root for it.