Just to put to bed the 'German Car Makers' myth.
David Davis, (before the referendum):
We are too valuable a market for Europe to shut off. Within minutes of a vote for Brexit the CEO’s of Mercedes, BMW, VW and Audi will be knocking down Chancellor Merkel’s door demanding that there be no barriers to German access to the British market. And this is not just German cars. The same will happen with Shell and Unilever in the Netherlands, EDF, EADS and the viticultural trade associations in France, Seat in Spain, and Fiat and the fashion designers in Italy
www.conservativehome.com/platform/2016/02/david-davis-britain-would-be-better-off-out-of-the-eu-and-heres-why.html
Unfortunately for Davis, he was as usual talking nonsense and none of his predictions came true. Unilever even moved their HQ from London to the Netherlands, taking their tax contributions with them.
VW sells 10 million cars a year worldwide. Of these, only 250,000 are sold in the UK, so less than 3%. For all German manufacturers the figure is less than 10% of sales, so although they don't want to lose the UK market, it is not as important to them as Brexiters claim.
But here's the ironic bit. Almost all cars currently sold in the UK are either imported from the EU or are assembled in the UK from components produced in the EU. Not just the obviously European brands (VW, Mercedes, BMW, Opel/Vauxhall, Skoda, Audi, Ford, Fiat, Seat, Dacia, Renault etc) but also the Japanese brands (Honda, Nissan, Toyota) are made in the EU, as are the less obvious brands such as KIA and Hyundai which are made in Poland and the Czech Rep for the UK and European market. After Brexit, the car manufacturers currently in the UK will be forced to relocate - e.g. Nissan is owned by Renault and will move to France or to Dacia in Romania, BMW already make Minis in Holland and have previously made them at Magna-Steyr in Austria, Jaguar/Land Rover have already built a £1billion plant in Slovakia (bigger than any plant that they have in the UK)
So post-Brexit, with no car factories left in the UK, almost all cars sold in the UK will continue to come from the EU, but actually in increased numbers to replace the lost UK production. Even the only American brand (apart from Ford Europe) selling in any quantity in the UK, Chrysler/Jeep, is owned by Fiat.
The EU companies will continue to sell cars in the UK - there are few alternative manufacturers, and people buying Mercedes, Porsche or BMW are not going to swap them for a Hindustan Ambassador. The downside for everyone, Brexiters and Remainers alike, is that we'll all be paying 20% more for the car (and the spares and servicing).