It said car makers, including Toyota and Nissan, had warned that a period of uncertainty would follow a Brexit vote, as trade and labour deals with Europe are renegotiated.
Toyota and Nissan said in the run-up to the vote that continued membership of the EU was preferable for their operations and that a vote to leave would create new challenges for an industry that employs some 800,000 people in Britain.
Jaguar Land Rover, owned by Tata Motors, is Britain's largest carmaker, followed by Nissan, which has been in Britain for three decades and makes 475,000 cars a year in the country, most of them for export inside the European Union and beyond.
Reuters said JLR has estimated its annual profit could shrink by £1 billion pounds by 2020 if Britain returns to World Trade Organization rules for trade with Europe.
Toyota produced about 190,000 cars in Britain last year, of which 75% went to the European Union.
BMW Group said there would be "no immediate change" to its operations in the UK following the country's decision to leave the EU and declined to speculate on any longer-term implications.
"Today, we know that many of the relevant conditions for supplying the European market will have to be re-negotiated, but of course we cannot say what this means for our UK operations until those future regulatory and legislative arrangements are agreed," a spokeswoman told Reuters.
"We will not speculate about the outcome of these negotiations nor about any possible effects that might have on our production operations in the UK," she added.
Aston Martin chief executive Andy Palmer warned that Britain's exit from the European Union was likely to require additional "productivity and efficiency" gains at the British sportscar make. He urged the UK government to secure tariff-free access to EU markets.
"We acknowledge the decision and the rule of democracy," Palmer said in a statement to Reuters after Britain's referendum vote to leave the European Union.
"Aston Martin will now orientate its business to deliver our mid-term plan in the context of the exit and the market volatility that may exist during the period of transition," Palmer said, adding that a weaker pound should "partially offset" the increased instability.
"As the UK could now be subject to new trade tariff barriers, we also anticipate the need for additional productivity and efficiency in the medium term," he said.
