In The Lucky Ones, three Army reservists are forced to share a rental car and their lives in a patch-quilt road flick that’s as uneven as their diary-of-life characters. After exchanging brief war stories, things get personal as viewers discover the quirky truths about our threesome.

Somber Fred Cheaver (Tim Robbins) is a military lifer with a bad back on his way home for good. Spunky Colee Dunn (Rachel McAdams), on a 30-day leave to recover from a shot in the leg, wants to return a guitar to the family of her boyfriend, who she thinks is an ex-con. Finally, there’s T.K. Poole (Michael Pena) who was hit in the groin by shrapnel and is headed for a specialist in Las Vegas to treat his ED before his girlfriend finds out.

Unlike the emotionally tugging Stop-Loss or In the Valley of Elah, or the ridiculously preachy and boring Lions for Lambs, director Neil Burger shoots mostly for humor in this talky post-war melodrama. The three vets all have enough emotional baggage to make things interesting without playing too heavily on the heartstrings. And each follows a sort of unwritten soldier’s code of right versus wrong convictions that makes them noble and likable.

McAdams keeps things light with her spirited performance as Colee, a feisty, opinionated high-school grad. Pena supplies the bravado and earthiness the film needs as T.K., and Robbins rounds things out as Fred, offering the insights and grey-haired wisdom of a married man facing the challenges of middle age with all its baggage.

The story by Burger and Dirk Wittenborn, however, often follows an unreal script that may leave viewers scratching their heads and wondering if this is a movie about vets or the TV series “Army Wives.” Fred’s wife Pat (Molly Hagan) is so neurotic that she wants a divorce. Never mind that her husband’s back from a war in one piece, or that her son finally made it into Stanford and needs money. Pat wants to tear the family apart, wasting the family’s energies and money on a divorce because she’s suddenly discovered she’s “happier” living alone.

Furthermore, Colee is often over-the-top as an uneducated wild thing with an absurdly misguided allegiance to her ex-con boyfriend. For someone wounded in combat, she’s far too tactless and aw-shucks goofy, telling a strange church congregation about the trio’s most intimate problems. This gets them invited to a rich guy’s party where audiences encounter the usual “why we’re over there” peacenik palaver.

Surprisingly, the syrupy storylines add some warmth and tenderness this film needs to keep it balanced, and the three personalities, diverse as they are, form a sort of combat unit against life. As one would expect, the life they come back to is filled with all sorts of predicaments. Like so many “coming home” war films, the big challenge for all three is to get back on life’s merry go round after spending a combat tour in an upside down world. The movie grapples with all sorts of social conundrums: loss of family, identity and the need to connect personally with another human being. Things often take a turn for the comedic, as when TK’s ED is cured after a run-in with a tornado, or when Fred’s bout of depression ends after some hot and noisy sex with a bored socialite.

The film ends not exactly the way one would want it to, but the climax does tie up all the loose ends and seems to solve everyone’s problems. While they make it to Las Vegas, our three heroes play the cards that life has dealt them and make the most of it.

The DVD (Lionsgate, MSRP: $27.98) only comes with a short but obligatory making-of featurette, “A Look Inside The Lucky Ones,” that gives viewers a glance at all the challenges that are typical in making a road movie.

The Lucky Ones is now available on DVD.