Nissan sells across Europe.
70% of the cars made in the Sunderland factory go to other EU countries.
If Brexit makes cross-border trade more expensive, basing its factory here means 70% of its cars face a cost. If it moved to e.g Frankfurt only 30% would.
AND they've already got factories on the mainland ready to expand if needed.
eastmidlandsbusinesslink.co.uk/mag/manufactur…