"Used Cars," a mean, spirited farce about cutthroat rivalry between ruthless used-car salesmen somewhere in the Southwest, recalls the worst tendencies of "Ace in the Hole" crossed with the worst tendencies of "One, Two, Three."

It's assiduously nasty and hard-driving too, a double-duty excess. Director/co-writer Robert Zemeckis has undeniable energy and flair, but it's being misspent on pretexts and situations that seem inexcusably gratuitous and snide.

"Used Cars," opening today at area theaters, relies on a grotesque plot. It culminates in a sequence of a huge car caravan riding to the rescue of the ostensible hero, Kurt Russell as a fast-talking, devious salesman, and the heroine, Deborah Harmon, who has inherited the imperiled dealership he works for. Pictorially expansive and rousing, this automotive stampede has the sort of humorous bulge and verve that John Landis strains for repeatedly in "The Blues Brothers."

But one couldn't care less whether the rescue succeeds, because the pretext has been feebly trumped up and the hero has been characterized as an unregenerate swine whose triumph is an endorsement of swinishness. Despite several opportunities to do so, Zemeckis and co-writer Bob Gale decline to moderate the selfish, obnoxious behavior that makes Russell's character unappealing and unfit for comic heroism. "Used Cars" leaves one in a foul mood, unwilling to brush off the insult.

Russell and Gerrit Graham are cast as desperate young hustlers employed at the run-down dealership of Jack Warden, a kindly proprietor with a weak ticker. Across the street there is a spiffy dealership owned by Warden's greedy brother (Warden again, now in a red toupee), who has connections in city hall and knows that the seedy lot will soon be worth a bundle. The bad brother, called Roy Fuchs, arranges for the good brother, Luke, to be taken for a ride -- by a stunt driver who poses as a customer and scares poor Luke into a coronary.

In the course of this alienating episode, Zemeckis attempts to give car-stunt fans their kicks while simultaneously terrorizing the one decent character in the story into a fatal collapse. Not smart and not amusing. The blunder is aggravated by pretending that it's clever of Russell to outfox the scheming brother by hiding his boss' body and eventually desecrating it to evade detection.

One of the victims of this desception happens to be the boss' daughter, Miss Harmon, who has returned after a decade of estrangement of a reunion that can't take place. The hero never does come clean with the heroine. Indeed, we're eventually supposed to take pleasure in the hint that after tying the knot, they'll see eye-to-eye about a really unscrupulous operation.

"Used Cars" has more than enough sight gags and car stunts to get whoops of pleasure out of customers prepared to let both the fimmakers and characters off the hook. It also has plenty of comedic acting talent in the presence of Russell, Graham, Frank McRaie as a demonic mechanic, David L. Lander and Michael McKean (the Lenny and Squiggy of "Laverne and Shirley") as criminally inclined electronics wizards, Al Lewis as a judge, Woodrow Parfrey as a high school teacher, Wendie Jo Sperber (one of the lively young performers introduced in Zemeckis' and Gale's "I Want Hold Your Hand") as a panicky driver's-ed pupil and many others. What it doesn't have a trace of conscience or generosity, and this absence takes an overwhelming emotional toll.

Robert Zemeckis and Bob Gale loomed as promising filmmaking newcomers on the strength of their first feature, "I Wanna Hold Your Hand," an exuberant comedy about New Jersey teen-agers in the grip of Beatlemania. The movie's failure appeared to be a studio blunder, and it never got a chance to find the public it deserved.

In the wake of their subsequent disreputable credits -- the deranged screenplay for Steven Spielberg's "1941" and now "Used Cars," a drastic revision is in order. Already specialists in cynical manipulation while still in their 20s, they present an example that aspiring young fimmakers would be well-advised to avoid.