Chancellor Gordon Brown has visited BMW's factory on the outskirts of Oxford to see the start of production of the firm's second-generation Mini.
Praising the staff, he said the ongoing success of the Mini was an example of how Britain "can compete and succeed in the global economy".
Since the first Mini was made at Cowley in 2001, the plant has steadily boosted output, hitting 200,000 cars last year.
The new Mini comes after Nissan said it will build a new model in Sunderland.
Nissan announced last week that it is to build a new small 4x4 car called the Qashqai at the plant alongside existing production of its Almeira, Primera and Micra models.
BMW's decision to make the new Mini in Oxford is creating an additional 200 jobs.
The trade union convenor at the Cowley plant, Bernard Moss, said BMW had now invested close to £1bn on Mini production facilities in the UK.
BMW is now also producing the petrol engines for the Mini in the UK at a plant in Warwickshire, after they were previously made in Brazil.
Almost one-in-six cars sold by BMW is now a Mini.
"This is a great day for Mini, a great day for BMW, and it's a great day for Oxford and a great day for Britain," said Mr Brown.
"The production of the new Mini will bring jobs, lead to investment and bring prosperity to our economy.
"It is an exciting symbol of a growing and dynamic economy across Europe."