The tinfoil-coated Volkswagen which stood at the front door of WASH ART '76 has this year been replaced by a gleaming gold Ferrari. This year's international art fair, the second in a series, is, as such things go, snazzier then the last.

More dealers are participating - last year there were 90, this year there are 130 from a dozen countries - and their temporary stalls at the D.C. Armory are, at least in general, filled with better stuff.

ART '77 (a.k.a. art Washington '77 and WASH ART '77) is less an exhibition, or a slew of exhibitions, that an art dealers' convention. The casual gallery-goer who plunks down his $3 for a day's admission has bought himself an eyeful (and may buy himself a bargain), but for the participating

Surrounded as they often are by suspicious artists and suspicious buyers, art dealers tend to be secretive, competitive and, perhaps, a little lonely. The international art fairs, those in Basel, Cologne, Dusseldorf, Paris, Bologna - and now the one in Washington - offer them a chance to hang out with each other, to guage the world's art market, to gossip, trade and learn.

Does a dealer, say, from London have a stock of Henry Moores? Maybe he can move them through a dealer in New York. If a dealer who's begun to move from paintings into photographs here picks up the name of three insatiable collectors, his business trip to Washington may prove a fine investment.

"The great benefit is exposure," says Washington's Diane Brown. "I get exposure for my artists, I get exposure for myself, and I can use the fair to funnel visitors to may gallery on P Street."

"The fair has been open for an hour, and I've already paid my way," said Jacques Kaplan of New York. Kaplan, once a furrier, used to trade fur coats for works by well-known artists of the New York school. "I have a very big collection of very small objects," said Kaplan, pointing to the paintings on the partition wall, small works by Juan Gris ($5,000), Man Rav ($6,000), Josef Albers ($1,500) and San Francis ($6,500)."I've already sold a Albers. I have a reserve on the Mark Tobey. One sale was amusing. I just sold that Foujita to an old friend from New York. I asked him, 'Why didn't you buy it there?' He told me he didn't know I had it."

"In this WASH ART '77," writes Elias A. Felluss, the father of the art fair, "over 130 galleries and publishers are represented from Brazil to Sweden, from Poland to Japan. They will meet in the relaxed halls of the D.C. Armory, not a holy temple of culture, but 76,000 square feet of atmosphere conductive to the business of art."

It should be said that Felluss, a 35- year-old Washington art entrepreneur, has confounded skeptics who doubted he was able to bring an art fair off. Some who were convinced the first would never open have bought booths for the second.

At Tuesday evening's opening Felluss walked the aisles in a blissful daze. "I haven't been to bed," he said, "for the last four days."

Though the words "the International Air World" may evoke an image of artistocratic dealers extracting priceless works from palaces and castles, the air fair shows its visitors that the International Air World is involved in retail trade. The art that is on sale there is generally no better, and frequently much worse, than that usually on sale in the better galleries of Washington.

One can find shlock posters at the art fair, as well as first-rate drawings by de Kooning, large expensive paintings as well as new and unsigned prints by Cezanne ($163), Renori ($113), Manet ($151) and Matisse ($113) that are recent restrikes made from plates those artists failed to destroy.

Those used to seeing pictures carefully displayed in well-lit gallerise and museums will carry from the art fair a rich and jumbled memory of the art world's nuts and bolts.

The fair will remain on view through Monday at the Armory. Day tickets cost $3 and six-day passes are $6. The Armory will be open Thursday and Friday from noon to 10 p.m.: Saturday and Sunday, 10 a.m. to 8 p.m.: and Monday, 10 a.m. to 6 p.m. Art students will be admitted without charge on Monday between 10 a.m. and 1 p.m.