The CEO of luxury automaker Jaguar Land Rover (JLR), Ralf Speth, has indicated the extra costs associated with Brexit could force the company to move production overseas. That follows similar comments from BMW and shows the reliance of automotive supply chains on regional regulations. Britain’s trade in completed vehicles with the EU reached 52 billion euros ($61 billion) in the 12 months to March 31. It’s already in a downturn with U.K. exports to the EU down 8% in the past year. Leaving the EU will also disrupt British automakers’ supply chains with other countries, including the U.S.,...