DETROIT, SEPT. 7 -- Ford Motor Co., which has been seeking an acquisition for some time, said yesterday it is buying British luxury automaker Aston Martin Lagonda Ltd., which makes five hand-built, $140,000-$170,000 cars a week.

The move is similar to purchases of prestige makers in the last year by General Motors Corp., which acquired Britain's Group Lotus Cars PLC, and Chrysler Corp., which bought Italy's Nuova Automobili F. Lamborghini SpA.

"Ford involvement will allow Aston Martin to expand its production capabilities and fully pursue future product programs," said Keith Whipple, Ford of Europe chairman.

"For Ford, it is an opportunity to enter the high-image specialty market where Aston Martin has earned an outstanding reputation."

No purchase price or closing date was disclosed. Aston Martin will retain its present management, Whipple said.

Ford, the world's most profitable automaker, earned $3.3 billion in 1986 and $2.9 billion in the first half of 1987.

It had about $9 billion in cash reserves and has been looking for something to spend it on.

Aston Martin's 400 employes spend 16 weeks on each car, applying 20 coats of hand-rubbed paint on its V8 Volante, V8 Vantage, the Lagonda and the V8 Saloon.

Aston Martin also is producing a limited 50-car edition of the Vantage Zagato, which has a top speed of 186 miles per hour.

Each engine is handmade and autographed by a single craftsman at Aston Martin's facilities in Newport Pagnell, England.

One of the 69-year-old company's best-known cars was the Aston Martin DB5, driven in many James Bond movies.

In its lifetime, Aston Martin has built just over 10,000 cars.

"Aston Martin has a distinguished history filled with distinctive cars and checkered-flag racing victories," Whipple said. "The company is long on automotive know-how and engineering expertise."

Aston Martin will introduce a new sports car at the end of 1988, he said.

The company was founded in 1919 by Lionel Martin and Robert Bamford in Henniker Mews, England.

The "Aston" in the company's name came from the Aston Clinton hill climb, an uphill race in which Martin drove another maker's car.