Dax Shepard puts his friends, fiance Kristen Bell, even his own vehicles to good use in “Hit & Run,” a fun little car-chase comedy that’s quite infectious — the good time clearly had by the filmmakers rubs off on the audience.

Done on a tiny budget, the movie’s stunts and chases are nothing much, but the lack of resources steers the story away from action and toward the characters, who are wry, irreverent, even endearing.

Screenwriter Shepard, the “Parenthood” co-star who directed “Hit & Run” with David Palmer, tailors the roles to suit his pals, including Bradley Cooper, Tom Arnold, Kristin Chenoweth and “Parenthood” co-star Joy Bryant.

Shepard stars as a guy in witness protection who took the name Charlie Bronson. A former getaway driver for a gang of bank robbers, Charlie betrayed his pals for a sort-of noble reason, but Shepard doesn’t play him as a hoodlum with a halo.

Now living in rural California with academic Annie (Bell), Charlie decides to break cover and drive her back to his old stomping grounds in Los Angeles, where she’s got an interview for her dream job.

Through the scheming of her old beau, Gil (Michael Rosenbaum), Charlie and Annie wind up pursued by his old gang, including Alex Demitri (Cooper) and Charlie’s ex-girlfriend, Neve (Bryant).

Arnold plays federal agent Randy, Charlie’s witness-protection minder. A hapless blusterer, Randy’s at the center of many of the movie’s physical gags.

Oddly for a road romp, the main charm of “Hit & Run” comes from the verbal exchanges, either when the characters are standing still or sharing strange intimacies during a high-speed chase.

Shepard and Bell make such a natural couple on screen that it’s easy to imagine them, right or wrong, living out a blissfully perfect relationship in real life.

Cooper’s an oddly engaging bad guy, his dreadlocks and gaudy red running pants setting him apart from the usual Hollywood heavy.

Shepard cast two of his own vehicles — a supercharged 1967 Lincoln Continental and his Tatum racing dune buggy — and he demands as much from them as he does of the actors. Our cars are extensions of our lives and temperaments. The fact that Shepard laid his wheels on the line puts an even more personal spin on the movie.