The boss of Jaguar Land Rover has warned Theresa May a "hard Brexit" will wipe out his company’s profits, resulting in the loss of tens of thousands of jobs.
Addressing the UK’s first Zero Emission Vehicle Summit in Birmingham directly ahead of the Prime Minister, Dr Ralf Speth described the prospect of a cliff-edge break with the EU as "horrifying".
He said if the "wrong decisions" were taken in the negotiations with Brussels, it could result in the "worst of times" for the UK while the cost to Jaguar Land Rover would be more than £1.2 billion a year.
His stark intervention follows similar warnings from other industry bosses, including Airbus and BMW, about the potentially damaging consequences of Britain’s decision to leave the EU.
Dr Speth told delegates: "If we make the right decisions this could be the best of times. If we make the wrong ones, they could be the worst of times.
"We are absolutely firmly committed to the UK, it’s our home. But a hard Brexit will cost Jaguar Land Rover more than £1.2 billion a year – it’s horrifying, wiping our profit, destroying investment in the autonomous, zero-emissions, we want to share."
He added that the loss of jobs would be "counted into tens of thousands if we do not get the right Brexit deal."
His warning came as Theresa May pledged a £106 million funding boost for research and development in zero-emissions vehicles.
The Prime Minister said it was her ambition to make Britain a leader in the green technology field, while making traffic pollution "a thing of the past".
She hopes to build "a global, outward-facing country outside of the European Union" while investing in Britain for the long term.
"That is why I have set this country an ambitious mission. To put the UK at the forefront of the design and manufacturing of zero-emission vehicles and for all new cars and vans to be effectively zero emission by 2040," she said.
May also used the event to hold round-table talks on driving more foreign direct investment into the UK.
She was also having discussions with leading supply-chain companies from Germany, the USA, Japan, China, Spain and India.