Exports of British-built vans, trucks and buses increased by more than 11% in the first half of the year, with almost all the vehicles going to the European Union, new figures show.
Almost two-thirds of commercial vehicles built in Britain were exported, with 27,800 out of the 43,700 produced sent to more than 45 countries across the world.
The Society of Motor Manufacturers and Traders said six of the top 10 markets for British-built commercial vehicles (CV) were within the EU.
Chief executive Mike Hawes said: "It's positive to see such strong growth in CV exports, however, with almost every British-built van and truck destined for Europe, this reiterates the critical need to secure a new trading relationship that ensures this important sector can remain competitive.
"The British and European vehicle manufacturing industries are highly integrated, and a beneficial relationship will take time to negotiate.
"This is why we need Government to seek an interim arrangement that will maintain our place within the single market and customs union until this can be achieved."
Israel topped the list of the largest markets outside the EU, taking 1.2% of exports, followed by Australia (1.1%), Hong Kong and Taiwan (both 0.6%) and New Zealand (0.4%).