Earlier this year Robert Redford gave us “The Old Man and the Gun.” Now Clint Eastwood offers what might be called “The Old Man and the Coke.” Both David Lowery’s film and Eastwood’s “The Mule” are adapted, rather loosely, from profiles about real people—the former from David Grann’s New Yorker article about geriatric bank robber Forrest Tucker and the latter from Sam Dolnick’s New York Times Magazine piece about elderly drug runner Leo Sharp—and serve as perhaps valedictory vehicles for screen icons. Both are also leisurely and ruminative. Lowery’s is the better film; while Eastwood’s is a distinct improvement over his last, the rambling semi-documentary “The 15:17 to Paris,” it still comes across as more flat and lackadaisical than genuinely introspective and revealing.

In the case of “The Mule,” screenwriter Nick Schenk, who also wrote Eastwood’s “Gran Torino,” has gone a highly fictionalized route. Sharp’s character has been rechristened Earl Stone, and has been relocated from Michigan City, Indiana and Detroit, to Illinois—specifically Peoria (where, one suspects, it will, according to the old line, play well) and Chicago. Stone remains, however, the champion hybridizer of day lilies that Sharp was—at least in the prologue set at the turn of the century, when he’s shown being feted at a flower convention while skipping the wedding of his daughter Iris (Alison Eastwood). Unhappily the rise of the Internet ruins his business and leaves him, a decade-plus later, broke, with his house foreclosed on by the bank.

Now homeless, he drives his packed pickup to the house of his affectionate granddaughter Ginny (Taissa Farmiga), who’s about to get married. There he encounters not only a furious Iris and his equally contemptuous ex-wife Mary (Dianne Wiest), but a wedding guest who offers him the phone number of a guy who’s on the lookout for unsuspicious-looking drivers willing to transport goods from Arizona to Detroit in their own vehicles for good cash. Anxious to earn money to pay for the cash bar at Ginny’s reception, Earl bites, and he so becomes the titular drug courier nicknamed Tata, turning what he initially intended to be a one-time gig into a permanent occupation as he aims to fill not only his needs—reclaiming his house, buying a new pickup—but those of others, like a contribution to reopen the recently burned-out Peoria branch of the VFW.

The details of Earl’s business dealings with his Mexican cartel associates—the fellows he picks up the drugs from; Julio (Ignacio Serricchio), his often exasperated handler; Laton (Andy Garcia), the kingpin who comes to like the old geezer so much he invites him to his estate for a party—are treated in a fashion that mixes modest tension with bits of humor, not only when his stay at Laton’s spread includes some frisky escapades with scantily-clad young women but in episodes that occur along the road, as when Earl stops to help a stranded family fix a flat or drags Julio to lunch at a favorite sandwich place.

The intent of it all is to allow Eastwood to play Earl as the sort of cantankerous old coot who might be a bit addled (or is at least pretending to be so), with some retrograde notions about race and cultural differences, but is still lovable and good-hearted beneath that crusty, non-PC exterior—and mentally sharp when he wants to be, as when he smears Ben-gay on his hands to ward off a drug-sniffing dog. You know—as if Earl were Clint Eastwood.

Juxtaposed with that plot thread are a couple of others. One centers on Earl’s attempts to reconnect with his family, trying to make up for the neglect of earlier years. The other involves the search for the mysterious courier by the Chicago office of the DEA, headed by a typically gruff chief (Laurence Fishburne) who pushes two agents—newly-arrived Colin Bates (Bradley Cooper) and his partner (Michael Peña) to catch the elusive mule. The scenes of their working with an informant to collect information on the cartel’s operations and identify the courier are among the movie’s dullest, particularly since they’re clumsily written and slackly directed (though, to be fair, they allow for one of the picture’s strongest moments, when a terrified Mexican-American guy is stopped along the interstate for questioning). That includes unlikely meetings between Earl and Colin at a motel and waffle shop.

The various strands culminate in a prolonged last act that’s meant to be both tense and emotional but winds up succeeding at neither. The complications involve an abrupt change in cartel management and a sudden serious illness in Earl’s family that, taken together, result in real danger for the old man; that’s conjoined with the success of the DEA operation in finally tracking Earl down. Bringing the different elements together necessitates some sad clichés (like the one about a person whose single instance of discomfort immediately becomes terminal). Even more damaging, it involves significant implausibility, not least in a failure to explain how an imminent threat of death simply disappears. And it all ends not in excitement, but with a simple, lethargic winding down.

Still, there’s Eastwood to enjoy, and while he doesn’t really bring much to Earl that we haven’t seen him do before, it’s pleasant to see him go through the paces again, even if his obvious physical frailty comes as a bit of a shock. Nobody else particularly impresses—Cooper, Wiest, Peña and Fishburne are all pretty much wasted, although Garcia gets another opportunity to exhibit his natural smoothness and a few of the lesser players are amusing even in stereotypical parts. Cinematographer Yves Belanger’s unfussy lensing and Arturo Sandoval’s modest but effective score are helpful contributions.

“The Mule” is well-titled—it moseys rather than sprints, and ultimately doesn’t offer much beyond the opportunity to see Clint Eastwood playing himself in front of the camera once more. For some, that will be enough.