On the contrary, we have voted to some out of a system where BMWs can be sold from the EU to GB without trade tariffs. Looking at one of Trump's ideas, we could think about putting a 20% tariff on cars imported from Germany.

The other question would be about GB based manufacturing owned by BMW. Take the Mini, for example.

I cannot find a more up to date source at short notice, but in 2016 the Independent newspaper reported that SIX British-based companies owned by BMW, including at the time Rolls Royce warned of British job losses in the event of tariffs being introduced after Brexit.

The same article stated that

For BMW Group, more than half of Minis built and virtually all the engines and components made in the UK are exported to the EU, with over 150,000 new cars and many hundreds of thousands of parts imported from Europe each year

This isn't the ravings of some commie, it is from the mouths of industry executives and managers.