The car giant BMW has followed plane maker Airbus in warning of the adverse consequences of Brexit.
BMW UK boss Ian Robertson told the BBC it needed clarity by the end of the summer. It makes the Mini and Rolls Royce in the UK.
Earlier, Airbus warned it could leave the UK if it exits the European Union single market and customs union without a transition deal.
The UK government says it is confident of getting a good deal for industry.
The customs union brings together the EU’s 28 members in a duty-free area, in which they pay the same rate of duty on non-EU goods.