It isn’t only the kids who will be asking “Are we there yet?” while watching this sleazy, gruesomely unfunny remake of Harold Ramis’ cherished 1983 comedy, which really marked the beginning of John Hughes’ rise as the great family-comedy writer-director of the eighties. The three sequels to “National Lampoon’s Vacation”—two of which were penned by Hughes, presumably on an off day—were nothing to write home about, but this reboot (from the team of Jonathan M. Goldstein and John Francis Daley, making their writing-directing debut after scripting “Horrible Bosses” and “The Incredible Burt Wonderstone”) is truly a disgrace to its source. Admittedly Hughes’s scripts for the series weren’t exactly models of sophisticated wit—these were slapstick farces, after all—but they had an underlying good-natured quality that Ramis, most notably, brought to the fore. Goldstein and Daley emphasize vulgarity and mean-spiritedness instead, trying only sporadically for the heart the first film had even when it was anarchic. “Vacation” is so scummy that one wonders whether Jamie Gross wasn’t hired as editor because of his surname.

After a credits sequence that already demonstrates the movie’s approach—snapshots of people on vacation humiliating themselves or others, with plenty of raunchiness on display—Goldstein and Daley set their story in the next generation of Griswolds. Rusty, the son of Clark (Chevy Chase) and Ellen (Beverly D’Angelo) originally played by Anthony Michael Hall and later by Jason Lively, Ethan Embry and Johnny Galecki, is now a pilot on a Chicago-based commuter airline and married to Debbie (Christina Applegate). They’re parents to two sons, sensitive teen James (Skyler Gisondo) and foul-mouthed, nasty tyke Kevin (Steele Stebbins). Rusty decides that they need an extended family outing to bond, so he rents an Albanian minivan called the Tartan Prancer for them all to travel to California’s Walley World, just as he and sister Audrey did years ago with their parents, with disastrous results. Along the way they’ll stop in Texas to visit Audrey (Leslie Mann), now wed to Dallas TV weatherman Stone Crandall (Chris Hemsworth), before winding up at a San Francisco bed-and-breakfast run by Clark and Ellen.

Even in the prologue in Chicago, the screenplay’s tastelessness is on full display in a sequence in which exits the cockpit during a flight, leaving the plane in the control of a senile co-pilot before repairing to the cabin to chat with a clean-cut family, only to stumble into uncomfortable positions with them as the aircraft lurches about. And once the vacation actually begins, all the legs of the journey and stops along the way prove catastrophic. They feature such lovely moments as the clan literally swimming in a pool of excrement, Debbie getting wasted and throwing up during a visit to her old sorority in Memphis, repeated run-ins with an apparently “Duel”-like tractor-trailer driver, and Rusty’s literally exploding a cow on the Crandall ranch, winding up drenched in blood and gore. None of these episodes exhibit the exquisite comedy of frustration—and undercurrent of imminent emotional explosion—that Hughes and Chase brought to Clark’s misadventures; they’re all simply coarse for the sake of being coarse.

And the characterizations are just mystifying. Rusty, who as Hall played him was a sharp kid, watching his father’s klutziness with a mixture of amusement and concern, has grown into nothing more than a garrulous moron, played by Helms as a simple buffoon whose stupidity is matched only by his obliviousness. Even worse is little Kevin, played by the smiling Stebbins as a mini-psycho-in-the-making who, among other things, enjoys putting a plastic bag over his brother’s head to see how long he can survive. (It’s a relief when James finally turns the tables and puts the pint-sized brat in his place.) It’s not the actors’ fault how these characters come across; it’s that of the writers, who also liberally sprinkle the dialogue with obscenities to turn what’s supposed to be a family comedy into a definitely R-rated farce that has more in common with “We’re the Millers” than its purported namesake.

As Debbie Applegate has to endure that sorority sequence, and Gisondo has to mug in exasperation and embarrassment far too often as poor, horny James, but the nadir of the picture, in terms of performances, certainly comes in the visit to the Crandall place. Set aside the fact that the location is specified as Plano, Texas—a highly-developed Dallas suburb that bears absolutely no resemblance to the location that production designer Barry Robison has come up with; that’s just typical ignorance. The more grievous problem is Hemsworth’s turn as the grotesquely oversexed Stone, whose drawl would automatically exclude him from a job at any station within a hundred miles of DFW. Sure, “Blackhat” was a disaster, but has it reduced his career to this? Mann and D’Angelo are wasted in their brief onscreen moments, and as for Chase, what one most notices is how enormous he’s become. Nobody else much matters, though Charlie Day, Ron Livingston and Norman Reedus are all stuck with doomed cameos. Apart from that Plano sequence, the tech credits are all unremarkable.

The last sound you hear before the closing credits of “Vacation” is that of a toilet flushing. That’s a fitting end to this unremittingly crude, frequently repulsive sequel to a fondly-remembered cable perennial.