Chris Custer is a car flake. It takes one to know one, as they say, and I think he may be worse than I am. I mean, what kind of an off-the-wall automobile nut has owned and raced such oddball marques as Deutsch-Bonnets, Fairthorpe Electrons, Berkeleys and Humber Super Snipes?

What's more, Custer, as he passes into middle age, remains unrepentant, unlike so many of us whose juices have run dry, the Porsches and Austin-Healeys of our youth having given way to Ford Crown Victorias and Volvo station wagons. I knew that was not the case with Custer when he roared up my driveway not long ago at the wheel of a snorting little skate he calls the "Rotus."

It was fat-tired and about the height of a high-top sneaker. British racing green was its livery, and tucked under the louvered long-nosed hood was a 3.5-liter aluminum Rover V-8. The Rotus barely seats two, and Custer was wedged in the shoebox-size cockpit, his ruddy, widely grinning face protected from the rain only by a small windshield. The Rotus was topless, despite the cranky autumn weather, and Custer had just completed a 300- mile journey from Frederick, Md., where he runs a Toyota dealership, through the mountains of Pennsylvania and New York.

A hundreds-of-miles, spur-of- the-moment drive is the sort of thing one does in a Rotus, which by its very nature triggers irrational acts on the part of a driver. Last year Custer leapt aboard a similar machine and blasted off for Southern California, making the coast in 41 hours, nonstop, solo.

A car very much like the Rotus -- the Lotus 7 -- started life 30 years ago in the fertile mind of Colin Chapman, then a struggling race-car builder operating out of the garage of his North London home. The lean, clam-shell-fendered little rag top was a schoolboy's dream of a sports car: tiny, lightweight, brash, nimble and slightly outrageous.

Chapman's designs were so extraordinary they began to catch the eye of industry types in Europe. Before long he had tipped the auto-racing world upside down with his brilliant, mid-engine Grand Prix designs that made race cars by Ferrari, Maserati and Mercedes-Benz obsolete overnight. In 1957, Chapman exhibited his little Lotus 7 roadster at the Earls Court motor show, and it was an immediate hit.

More than 3,000 Lotus 7s were built before Chapman died, quite unexpectedly, long after his multimillion-dollar Group Lotus Car Companies Ltd. had entered into serious production of high-priced exotic sports cars. A number of tiny firms, all run by enthusiasts such as Custer, are constructing replicas of the lovable little rocket, both here and in Great Britain.

Custer is the perfect sort of person to be building a 1,300-pound, overpowered automobile with no doors: His background demands a certain unconventionality. He is the great-great- grandnephew of one George Custer, who was also known for engaging in somewhat bizarre and one-sided enterprises. Like his kinsman, Custer appears to enjoy his underdog status. So far, his tiny Frederick factory has produced a mere 44 Rotuses in the seven years he has been in business, about the number of automobiles giants like Ford and GM might misplace in a single day.

"I think there is a strong potential for selling 100 cars a year," Custer says, noting that an importer has expressed interest in selling 30 to 40 of the mites in Japan. His version of the car, by the way, is called Rotus to avoid plagiarizing the Chapman brand name and in deference to the Japanese difficulty in pronouncing the letter "l." "There is a certain poetic justice in being able to sell the Rotus in Japan," the Toyota dealer chuckles.

For anyone seeking classic, wind-in-the-kisser sports-car laughs, there is nothing better than a Rotus. It is the zappiest skate of an automobile on the road (Chapman once described his original Lotus 7 as a "four-wheeled motorcycle"), and one cannot drive the thing without being transformed into a nascent Formula One hero. The steering is bow-string taut, as is the stiff, independent suspension. The engine is up front, and the drive wheels are in the rear. There is so much power (0-60 in 6 seconds, 11.8 seconds in the quarter- mile, 130-mph-plus top speed) that normal cruising can be done by employing only second and fifth in the five-speed gearbox. For the faint of heart, Custer will happily substitute a Mazda rotary or Ford, Nissan or Toyota four-banger for the 225-hp Rover V-8 (that, incidentally, is the same horsepower found in the Ford Mustang GT, which weighs 2 1/2 times more). Depending on power plant, a Rotus costs $19,000 to $23,000, convertible top and side curtains included. Custer's Rotus differs from the original Lotus 7 in that it has a stronger, reinforced tubular chassis and a radically redesigned and updated suspension system. The body work is aluminum and fiberglass. The Rotus' safety components are limited to a shatterproof windshield, side-door beams, a roll bar and seat belts. (Federal regulations are different for cars of limited production.)

"I have never taken myself too seriously," confesses Custer, who has raced all manner of cars, airplanes and motorcycles over the years, in addition to having managed a small symphony orchestra. "The Rotus is designed for pure driving fun. You simply can't own it if you don't have a sense of humor."

Most nights, when all the Corollas have been put to bed, Custer can be found in his Rotus shop, welding tubular frames for another slightly mad customer who will surely undergo some kind of rebirth the first time he crams himself behind the wheel, peers out over the long, low hood, cranks the engine, hears the impudent blat of the exhaust and finally tromps on the throttle. Custer understands. So do I. And as long as there is a car like the Rotus and a few car flakes to carry the banner of totally irrational motoring, I reckon we can hold the technocrats and the social engineers at bay for at least a few more years. Charge, Custer! ::