About 150 BMW Oxford suppliers in Britain have attended a crash course in customs clearance procedures.
They have not had to worry over this as Britain was in the EU but if it leaves the car maker says they will need this information.
There’s a split developing in Europe over retaliation to US trade tariffs.
Germany says it wants to negotiate a deal with America because its car industry would be severely threatened but France says it expects the rest of the EU to adopt a united stance over penalties.
A secret report from America covering what VW knew of emissions cheating will be made public in Germany after the car-maker lost a bid to keep it confidential.
It comes as Nissan admitted it found more misconduct by employees emission testing engines in Japan, the second case in 12 months, and shares have been hit as a result.
Daimler has stopped deliveries of some lorries with discredited emissions and higher than permitted nitrogen oxide levels.
The company is talking to authorities in Germany about rectifying the mistakes and its use of Adblue which can create smog and ozone in certain conditions.