You have to give Drew Barrymore points for chutzpah. In her new picture, an adaptation of Beverly Donofrio’s autobiographical 1990 book, the 26-year old actress plays the central character from age 15 through 35. (Happily, she at least doesn’t attempt in the initial scene to portray the 11-year old Beverly, leaving that to Mika Boorem, whom one may remember as the tomboy of “Hearts in Atlantis.”) It’s a daunting task, and Barrymore comes through it remarkably well. She’s obviously too big and well-developed to be a very convincing high school sophomore from a purely physical standpoint, but she’s got the energy and naivete down. And at the other end of the age spectrum, she seems by her mid-thirties to have turned into a mid-eighties version of Bette Davis–not a terribly attractive sight, and more a stunt than a persuasive impersonation. But she tries hard, and one must respect the considerable effort she expends.

Unfortunately, it’s all in the service of a story that seems a scrubbed-down telling of a life that must have been much harsher and bleaker than it’s shown to be here, a narrative that’s been Hollywoodized to a distressing degree. In that respect one might compare the result to “Erin Brockovich,” which was similarly sanitized and neutered. And as with Julia Roberts’ performance in that film, Barrymore’s ultimately comes off as an acting exercise more than an authentic recreation. By the close one isn’t so much amazed at how well she does it, but that she does it at all.

Another way in which “Riding in Cars With Boys” will probably resemble “Brockovich” is that it’s likely to be a hit, especially with the considerable segment of the moviegoing public that responds favorably to pictures about Strong Women Who Achieve Their Dreams, particularly when the story also includes a Precocious Child who, sitcom-fashion, is always Doing and Saying Adorable Things. Donofrio, you see, isn’t the only person who ages in the course of the picture. So does her son, though a single actor doesn’t attempt Barrymore’s trick of aging across the spectrum. Baby Jason is portrayed by Briana Tilden, who’s succeeded at one by Skye Arens, at two by Patrick and Robert Salerno, at three by Logan Arens, at six by Cody Arens, at eight by Logan Lerman, and finally at twenty by Adam Garcia. (Lots of paychecks, it would appear, for the Arens family.) At the earlier stages the kid is almost nauseatingly cute, and even as an NYU student he still has a puppy-dog aura about him. That might make him nearly intolerable to a few of us, but audiences who respond to sappy sitcoms will doubtlessly embrace him.

Jason’s depiction is characteristic, unhappily, of the treatment given all the material by Penny Marshall, a director to whom subtlety has always been a foreign quality. The tale of a smart Connecticut girl who gets pregnant by a laid-back wastrel named Ray (Steve Zahn)–to the understandable discomfort of her straight-arrow cop father (James Woods) and her strong-willed mother (Lorraine Bracco)–and who marries the dad, putting her own dreams on hold, to her endless frustration, could have made for a stark, realistic film. But that’s not what Marshall has opted for. Her picture is basically a light, often farcical ode to motherhood as much as to female strength, and it tries to win over its viewers by concentrating on colorful eccentricities and very heavy-handed sentiment. One sees the result not only in Barrymore’s performance, which is too frequently over-the-top, but in Zahn’s; this able farceur becomes virtually a stand-in for Crispin Glover as he’s asked to lay on the lovable oddness really thick (his aging, moreover, consists mostly in a variety of changing hairstyles). The same degree of overstatement is discernible in the work of Woods and Bracco, as well as in the performance of Brittany Murphy (late as the troubled patient of “Don’t Say A Word”) as Fay, Beverly’s long-term best friend.

There are, to be sure, laughs to be found in “Riding in Cars With Boys,” but they’re the sort of easy laughs that play at the lowest comic level. And the emphasis on Jason, particularly in his younger stages, appeals to the cheapest emotions; scenes of the kid mugging and saying sweet things will certainly extract lots of “aahs” in unison from appreciative audiences. But the movie is really a late twentieth-century version of the sort of story about a hard-working mom and her cute-as-a-button kid that was a staple of Fannie Hurst-style weepies in the thirties and forties. It’s played more for charm and humor here than it used to be, but the extent of the calculation and mawkishness is nearly the same. This is a trip that has an entirely predictable destination, and tugs far too insistently on the heartstrings in getting there. It may have the desired effect on you, but you’ll know you’ve been had when it’s over.