If you follow the automotive industry, you will be aware that - in simple terms - by the end of this year European manufacturers have to hit a fleet emissions average of 95g/km of CO2 for the cars they sell across the region or face huge fines.

While no manufacturer has stuck its hand up and admitted it will miss the target, a report by industry analysts JATO Dynamics has projected the bill for the industry could be as high as 34 billion euros (£29bn).

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The threat of these fines is why the number of plug-in hybrid and electric cars being put on sale is growing exponentially; without mass registrations of these technologies the car makers are in big trouble.

It is a huge problem exacerbated by the collapse in lower CO2 (but higher NOx and particulate) diesel sales, the switch to more stringent WLTP testing and the growing sales of bigger, heavier SUVs. A look at today’s UK-specific figures show highlights that, with the average CO2 figure for cars sold in the past three years rising again.

It’s a major headache for all car makers, albeit still with some opportunities to get out of jail: several manufacturers are already buying credits from car makers with sub-95g/km outputs, for instance (the most high profile being Fiat-Chrysler buying from Tesla) and there are rumours of car makers switching their entire company fleets over to electrified vehicles, to ensure they are part of the registration pool in the event of the car buying public not flocking to buy into the new technologies.

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From a UK perspective, however, what’s crucial is that - for as long as we remain in the EU and are negotiating our withdrawal - we are part of an European average figure, so manufacturers can offset our figures (127.9g/km last year) against those of other countries, such as electric car loving Holland and Norway, or small car loving Italy.

Potential disaster looms for 2021, however, when PM Boris Johnson has vowed our agreement to leave the EU will be enshrined. While current evidence suggests Johnson is not, as promised, dead in a ditch, and therefore his avowed timelines should be treated with caution, it is causing considerable concern among industry insiders that at that point the UK would mirror the EU’s legislation, but in isolation.

In other words car makers present in the UK market would have to hit the 95g/km target in the UK alone - or face the same fines as they will for their European-wide sales. And, before anyone says it, Brexit is not about to let them off the hook: no UK government is about to backtrack on environmental targets, and this one has already agreed to mirror EU rules on this point.

Admittedly - and necessarily - crude maths by the Society for Motor Manufacturers and Traders (SMMT) has suggested that to hit that target BEV registrations would have to rise from 1.6% to 27% of the market, or alternatively-fuelled vehicle registrations from 7.4% to 56% of the whole market, assuming petrol and diesel registrations remained constant. Even at today’s exponential growth in interest in electrified cars, and with the multiples of more vehicles being offered, that seems at best optimistic.

Potentially, there will be mayhem.