As the discussion about Nissan and the effect of Brexit on its Sunderland plant rages on, maybe some dispassionate commentary is warranted. Note that this is not any different from what I wrote years ago, so tune out if you want to (thread)
The discussion is about consequences of a no-deal situation, so the question: what happens to the car industry (and many others) if there is NO FTA between the EU and the UK.
Both the EU and the UK will have to charge their so-called “MFN Tariffs” on goods imported from the other side. For cars - that means 10% both for the EU and the UK 
Add to that the administrative hassle involved. Basically: imports from the EU to the UK face additional costs and imports from the UK to the EU. What’s the effect?
Logically, goods that are EU (on the EU side) and goods that are UK (on the UK side) have advantages over imported goods. Companies will have to adapt their strategies to that.
The effect should be relocation on both sides. However, there’s a scale effect.
This is particularly relevant where production is as a whole generally (yes, simplifying, of course) on a regional basis. If you produce for the European market, if 80 % of your cars are sold in the EU, you have to make sure to stay competitive there.
So where would you locate a green-field investment? You will compare all possible sites and if your market is EU, a UK site will have a 10% cost disadvantage from tariffs (plus some for admin). If your market is UK, vice versa.
Of course, if you already have a production site, considerations change. You already have invested billions. Withdrawing them does not seem an obvious choice either. So you might want to segment markets in the future etc. Etc.
The overall effect - economics tells us - is that if you are producing for the whole EU you will on balance not do it in the UK in the long run. So says the utterly pro-Brexit economist (and go-to economist for the economics benefits of Brexit) Minford
That, of course, does NOT mean that on-shoring does not go both ways. It should. The UK is a large, significant market. And logically car companies will want to serve it. It is just that global car companies will on balance not use it as a production site for the EU for no-deal.
It is only proper to ask @SMMT and @TradeAlemaro whether any of this is fantastically off the mark.
(Note that we will have to live with “I told you so” and “you were wrong” shouts from both sides of the Brexit debate for years to come... This thread is about overall impact and incentives.)
(And finally: this thread is NOT about Brexit overall. If you want to rerun the Brexit debate, please do it elsewhere. The UK left the EU. In the past.)
