The UK automotive trade association SMMT says that getting a departure deal with the EU must be the next UK prime minister's first job as it warned of a GBP50,000 a minute cost due to potential border delays in the event of a hard or no-deal Brexit.

The UK's governing political party – the Conservative Party – is currently electing a leader who will serve as the next prime minister, following on from Theresa May who has said she is standing down. The contest is between Boris Johnson and Jeremy Hunt with the result still weeks away.

The UK is currently due to leave the EU on October 31st.

The SMMT said a new report suggests the 'right deal, the right business environment and auto-friendly trade strategy' could deliver a GBP20bn boost as the auto industry in Britain maximises its potential.

The SMMT warns that leaving the EU without a deal would trigger 'the most seismic shift in trading conditions ever experienced by automotive, with billions of pounds of tariffs threatening to impact consumer choice and affordability'. It said the end to borderless trade could bring crippling disruptions to the industry's just-in-time operating model. Delays to shipments of parts to production plants are measured in minutes, with every 60 seconds costing GBP50,000 in gross value added – amounting to some GBP70m a day in a worst case scenario.

Combined with WTO tariffs, which for trade in passenger cars alone amount to GBP4.5bn a year, the SMMT said 'this would deliver a knockout blow to the sector's competitiveness, undermining a decade of extraordinary growth.'

Thanks to the free and frictionless trade afforded by the customs union and single market, automotive trade value has risen by 118% since the global financial recession, from GBP47bn in 2009 to GBP101bn last year. Over the same period, car production increased by more than half, with more than eight in 10 vehicles bound for export – the majority to the EU. Some 3.3m new cars are traded between the UK and EU each year, while the UK exports some GBP5.2bn worth of components and GBP2.9bn of engines to help build vehicles across the continent.

Addressing an audience of business leaders and government officials at the industry's annual International Automotive Summit in London today, Mike Hawes, SMMT chief executive, said, "Automotive matters to UK trade and to the economy, and this report shows that, if the right choices are made, a bright future is possible. However, 'no deal' remains the clear and present danger. We are already seeing the consequences of uncertainty, the fear of no deal. The next PM's first job in office must be to secure a deal that maintains frictionless trade because, for our industry, 'no deal' is not an option and we don't have the luxury of time."

Automotive is the UK's single biggest exporter of goods, trading with some 160 countries worldwide, and accounting for more than 14% of total exports. The sector is one of the country's most valuable economic assets, directly employing 168,000 people, supporting communities and delivering an annual GBP18.6bn to the public purse. The SMMT maintains that leaving the EU without a deal would jeopardise this, hampering government's ambitions to boost global exports and GDP. Without automotive, the UK would lose its hard-won status as the world's 10th biggest exporter of goods, falling to 14th place behind Belgium, Canada, Mexico and Russia.

However, the report also calculates that the right deal, backed up by ongoing collaboration to create a competitive business environment and thriving market, and combined with an ambitious automotive-focused trade strategy, could trigger a 20% uplift in the industry's global trade value – worth GBP20bn, if the sector can maximise its full capacity.