The EU Referendum vote remains a sensitive subject, while negotiators have given little away as regards to what any Leave deal will look like.

But companies with car plants in the UK are increasingly worried that leaving the EU will also mean leaving the single market. If that happens, they suggest, it will be significantly more expensive to build cars on these shores.

Recent success in the industry hinges on being part of the single market, according to Mike Hawes, the chief executive of the Society of Motor Manufacturers and Traders (SMMT), who spoke to the BBC recently.

He said: "Don't be blinded by the good news that you're seeing not just around our sector but around business in general. We're very concerned that the future state of the automotive industry and the success could be jeopardised if we're not in the single market."

Hawes was at the Paris Motor Show, where he supported an event organised by UK car makers to warn against Britain leaving the single market.

Models from Jaguar, Aston Martin, Vauxhall, Nissan, Mini, Toyota and McLaren were on show in the French capital.

The components of these cars are made across the EU as well as in the UK. Many are moved back and forth over the Channel as they are added to by other plants and turned into different finished products – a phenomenon which makes car manufacturing highly vulnerable to tariffs.

Access to the single market means there are no tariffs.

Will some car brands become too costly to build in the UK? Worries over any deal that leaves the UK out of the single market puts many car brands in a precarious situation. While artisan cars such as Rolls Royce and McLaren might be able to add 10% to their sales price, firms like Nissan and Vauxhall are built on the premise of being affordable.

Around 160,000 people are directly employed by carmakers, with another 799,000 employed across the wider sector.

It seems negotiators have a tough job balancing the needs of the automotive industry with the political will of the public.