THEY'RE PLAYING OUR SONG; book by Neil Simon; Music by Marvin Hamlisch; lyrics by Carole Bayer Sager; directed by Robert Moore; scenery and projections by Douglas Schmidt; costumes by Ann Roth; lighting by Tharon Musser; musical numbers staged by Patricia Birch. With Victor Garber and Marsha Skaggs.

America may no longer be competitive when it comes to making automobiles or TV sets, but I defy anyone to name the country that can produce a better Neil Simon play than we can. Has a Neil Simon play ever been accused of emitting dangerous radiation, or not starting in the cold, or not having enough raisins in the box? Of course not. Because this is one manufacturer who still keeps a close watch on his assembly line and still monitors the performance of his product in the field.

Strickly speaking, "They're Playing Our Song," which opened Saturday, is not a play but a musical. It has music by Marvin Hamlisch and lyrics by Carole Bayer Sager, who are said to have been the models for Vernon Gersh and Sonia Walsk, the songwriting and romantic duo who comprise the entire cast of characters. So you might expect to find more of Hamlisch and Sager than of Simon here, but as it turns out, "They're Playing Our Song" is more a comedy with music than a musical, and the comedy is the pure, uncompromising, instantly recognizable work of the man who gave us "Barefoot in the Park," "The Odd Couple," "The Sunshine Boys," "Chapter Two," "Plaza Suite," "California Suite" and all the rest.

When someone delivers such astonishingly consistent products on such an astonishingly regular schedule, criticism becomes redundant. Whether you count yourself one of Simon's admirers or one of his detractors -- whether his jokes make you laugh or grit your teeth, or perhaps a little of both -- you know what to expect. And what you expect is what you get from "They're Playing Our Song," a slick concoction that is guaranteed to draw legions of laugh-starved Washingtonians to the National Theater.

Vernon and Sonia, Crisply played here by Victor Garber and Marsha Skaggs, meet as prospective collaborators. Vernon, the composer, is cautious, egotistical and rich. Sonia, the lyricist, is reckless, self-doubting and (by Broadway standards) poor.

And she hasn't quite finished extricating herself from a five-year involvement with an unseen character named Leon, who has a way of popping in or up whenever the Vernon-Sonia relationship seems to be headed somewhere. Toward the end of the first act, for example, the relationship seems to be headed for a weekend on Long Island, and everything is looking like the title of the song they have just sung -- "Right." Then Vernon takes a wrong turn, his car breaks down, he strains his back pushing the car the last few miles, they stumble into the wrong beach house, and just when they decide to forget their troubles in their unknown host's bed, the phone rings. It's Leon calling.

All of this is punctuated with the usual, awesomely nonstop Simon repartee.

Visiting Sonia's apartment, Vernon reaches into a bowl, stuffs a handful of something into his mouth, and exclaims: "Oh, I love these little pebble candies."

"No, they're just pebbles," she replies, and he spits them onto the floor, not a moment too soon.

Sonia has been forced to suspend visits to her psychoanalyst because, she explains, "He's in Mexico, getting divorced." His shrink, meanwhile, has died, which inspires her to observe: "If you went to the funeral, he probably charged you for the hour."

And when they decide to live together, Vernon's first question is: "You don't wear jockey shorts, do you? I hate getting underwear confused."

Was this the sort of dialogue that flowed between Hamlisch and Sager as they got to know each other? If their score is any evidence, perhaps not. Simon has Vernon criticize Sonia for a contrived rhyme in which two tennis buffs sing of playing "two sets in Massachusetts," but there is no such lyrical tomfoolery in these songs (some supposedly written by Vernon and Sonia, and some sung in character). Nor is there any of the concern for character and detail characteristic of "A Chorus Line," another show-business score on which Hamlisch colaborated (with Edward Kleban). Instead, Hamlisch and Sager have recreated, all too accurately, the sort of nondescript pop music made for Johnny Mathis and office-building elevators.

One memorable exception, to my ear, is "Fill in the Words," in which Vernon laments that "I'm never quite able to say what I feel" and delicately relates a composer's professional and personal feelings of imcompleteness. Here, for once, we have a plausible glimpse into a songwriter's life and the trials of collaboration. And the number is greatly enhanced by the way Robert Moore has staged it, with Vernon playing a tiny red grand piano, accompanied by his chorus of three spirits and their pianos.

Although I missed the Broadway production of "They're Playing Our Song" (with Lucie Arnaz and Robert Klein), it doesn't seem that any corners have been cut on this touring edition. Garger and Skaggs are attractive and skilled performers, and the show seems determined to compensate for its small cast and story with expensive visual razzle-dazzle -- elaborate sets, inventive projections, a turntable and the first automobile on a Washington stage since (if memory serves) "Night and Day."

The show is conspicuously miked, with the result that Garber and Skaggs scarcely have to exert themselves vocally -- and, alas, scarcely do -- while the orchestra seems to generate its sound from the speakers along-side the stage rather than the pit. Sooner or later, the gods must put a stop to this. sAnd while they're at it, maybe they could look into why rents are going up and candy bars are getting smaller.