The first of a new generation of Nissan Micras rolled off the production line on Wearside on Friday.
The Sunderland plant, which employs almost 5,000 people, has undergone a £235m renovation to make the new car.
More than 160,000 of the new vehicles will be built on Wearside.
But the company's president and chief executive Carlos Ghosn has again warned the long-term future of the plant depends on whether Britain adopts the euro.
Prime Minister Tony Blair was on hand to start the new production line rolling in Sunderland.
He praised the workforce for ensuring the plant's place at the top of Europe's car production league.
But Mr Ghosn told BBC News that future investment in Wearside would be difficult if the UK stuck with the pound.
He said: "Sunderland will become less and less important in Nissan's European operations."
The new Micra will appear in showrooms in January.
Motoring writers from all over Europe have praised Nissan's first joint venture with Renault.
Two years ago, Nissan decided to produce the Micra in Sunderland rather than in France where both its costs and its revenues would be in euros.
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