Cab companies in the Washington metropolitan area seem to come in two sizes: small and very large.

A. P. Cayton runs one of the large ones. Bluebird Cab Co., which Cayton and two other partners own, has overshadowed its competitors in Prince George's County for several decades, Cayton said.

It is one of a handful of dominant cab companies in the Washington area, including Barwood Cab in Montgomery County, the Red Top-Arlington Yellow Cab combination in Arlington County and two Alexandria companies, Yellow Cab and Diamond Cab.

The small companies with several dozen cabs or less are accustomed to a tough, hand-to-mouth struggle. Now, even the owners of the big companies are starting to sound pounded down by gasoline prices, repair charges and the ballooning costs of new cars.

"It's really put a knock on the business," said Lee Barnes, vice president of Barwood, which owns 220 cabs and leases its name to 60 independent drivers who drive their own cabs.

"We could have been out of business four years ago if we didn't have our own garage," said Cayton. Bluebird owns 110 taxicabs (it also leases its name to 45 independent drivers). The costs of repairing and patching up Bluebird's taxi fleet require the company to cannibalize its most damaged autos -- taking an axle from one wreck, a tie rod from another -- to keep the better cars on the road at a reasonable cost.

Owners like Cayton in Prince George's County might be expected to dwell on their misfortunes right now, when the county government is considering an increase in taxi fares. But there's evidence that they aren't crying wolf.

The number of cab companies in the United States -- now about 5,000 -- has been declining by about 100 a month during this year's recession, said Al LaGasse, head of the International Taxicab Association. "The industry is in a bind," said LaGasse.

New taxis this year will average $6,000 apiece, before being painted in the companies' colors, and before a radio is installed at a cost of $400 or more, Cayton said.

Even more painful, in the long run, are the wholesale changes in bodies, engines and parts as U.S. automakers step up complete retooling of their model lines to make them lighter and more fuel-efficient.

Cayton said he could take a windshield or door from a junked 1973 or 1974 Dodge stored on his lot and use them as replacement parts for a 1979 Dodge that had been in a minor accident. The retooling of the 1981 models will cut hard into that flexibility, he said.

The pressures on the cab fleet owners flow down the line, to the drivers.

"The price of gasoline has nothing to do with whether we win or lose," said Cayton. "But it can strangle the drivers."

The burden is greatest on the drivers who do not own their own cars, but rather lease them from large cab companies like Bluebird or Red Top Cab in Arlington.

Cayton will lease a Bluebird cab to a driver for $29.50 a day and the driver buys the gasoline. If the car is a 1974, eight-cylinder Dodge, a driver working 10 to 12 hours may spend $15 a day on gasoline -- thus paying at least $45 a day just to get started. On top of that are heavy insurance premiums, and only after paying those charges does a driver start working for himself.

The leasing charges elsewhere outside the district are comparable, although many are higher in the area, reaching as high as $35 a day.

Most cab companies -- like Barwood in Montgomery County -- lease a cab to a driver for a minimum six-day week, permitting the driver to operate Sunday, the seventh day, at no charge if the driver chooses. The mandatory six-day leasing period puts pressure on the drivers to keep busy, said Barnes. "It provides the best incentive," says Barnes. Barwood suggests that drivers work at least one rush hour. Most have to work both morning and evening periods to make a living, he said.

It's less and less of a living.