Volkswagen’s ‘group nights’ have become a fixed point on the global motor show circuit.

The night before a big motor show opens, VW commandeers the biggest exhibition hall in town (one year, converting Beijing’s Olympic swimming pool) and rolls out never fewer than eight or nine concepts or new models from its 12-brand line-up.

The night before this week’s Paris motor show was no different. I watched from the stands as cutting-edge concepts such as the VW XL Sport and Lamborghini Asterion were driven up the ramp.

But perhaps the production-destined new Volkswagen Passat plug-in hybrid was the most important car at the exposition.

This – rather beautifully built – machine is just the sort of car that will become a much more familiar site on our roads by the end of the decade.

As the factory cost of hybrid transmissions falls and the cost of building ‘clean’ diesel engines increases (as well as the potential backlash against diesel pollution), mid-range hybrids such as this will help VW meet the EU CO2 ‘fleet’ target of 95g/km by 2020.

But once the razzle-dazzle was over, VW boss Martin Winterkorn stepped forward to deliver to EU legislators and politicians the most nuanced and diplomatic warning you are ever likely to hear.

The edited version was quite simple: before you set fleet CO2 targets for beyond 2020, give the industry a two or three-year breathing space.

Winterkorn pointed out that unless real consumers start to buy hybrid and battery electric vehicles in numbers, improving on the 95g/km Co2 average would be commercially impossible.

“Climate protection doesn’t come free,” as he put it. The upshot, is that the plug-in Passat – and cars like it – might yet mark the technical peak for the mass-market car.

You can’t, as Winterkorn didn’t quite say, force people to buy these low CO2 models. While he repeatedly stressed that VW was ‘rigorously’ in favour of the 2020 95g/km target and the ‘greening’ of its factories, his killer fact was that reducing CO2 output by 1g/km required VW to invest of “100 million euros every year”.