BERLIN (Bloomberg) -- BMW Group CEO Harald Krueger said a UK vote to exit the European Union would cloud the future of its UK brands Mini and Rolls-Royce.
"I'd find it very regrettable," Krueger said Tuesday in a briefing at the Geneva auto show. "What it might mean is hard to tell. BMW has Mini, Rolls-Royce and an engine plant in the UK. It's critical that there'd be a trade agreement -- and what sort."
The UK is a valued member of the EU as "a driver for market liberalization and other reforms," the CEO said.
Oxford-based Mini has been owned since 1994 by BMW, which revived the brand with a new-generation car in 2001, while the German company bought licensing rights to Rolls-Royce in 1998, setting up the ultraluxury brand in Goodwood, southern England.
A clutch of other carmakers also used the Swiss show to register their concern about a breakup of the EU, with Daimler CEO Dieter Zetsche echoing his BMW counterpart in saying a UK exit would be "very, very regrettable."
The CEOs of PSA/Peugeot-Citroen and General Motors Co.'s Opel, which makes cars in the UK under the Vauxhall name, warned of a likely slump in sales tied to a weakening in the pound, leading to an earnings dip.
The country is Europe's second-biggest car market and the third-biggest producer in the region.
"Prices will go up to compensate for a weak currency, like in the emerging countries," PSA CEO Carlos Tavares said at the show. "The market as a whole will be impacted."
A manufacturing presence in the UK at least provides a degree of hedging against currency changes, though sterling "still is an issue," said Opel head Karl-Thomas Neumann.
At Ford Motor Co., which ended vehicle assembly in the UK in 2013 but still employs 14,000 people in the country, with engine and transmission plants there, European chief Jim Farley said an exit would be "unprecedented" and that it's too early to assess the likely consequences.
The comments come as Prime Minister David Cameron seeks to convince voters that a deal struck with EU counterparts warrants staying in the bloc ahead of a referendum planned for June 23.
JPMorgan said Tuesday an exit could halve the UK's growth rate to 1 percent in the year after an "out" decision, and weaken sterling as much as 10 percent.