But the problem is not limited to diesels. The high-efficiency GDI (petrol) engines producing eg. 125 bhp from a one-litre engine or 150 bhp from 1.4 litres emit huge amounts of particulate. While these engines have been around for several years now, car manufacturers have been given until 2017 to introduce filters.

We have 2 petrol cars fitted with direct injection engines, one a Nissan the other a Seat. Whilst the particle emissions are probably higher than a non-direct injection engine of a similar capacity they are way short of diesels. But particle filters for petrols are way simpler and cheaper to produce than diesel ones and the higher exhaust temp pretty much means that regens are constant. Not going to panic. What will be will be.

The US seems very keen on forcing re-calls of cars made by non-US companies, and this is just another example.

Possibly diesel and petrol engines are reaching the limit of how clean they can be made, practically.

Diesel engines are the most efficient type of internal combustion engines, which is why they're fitted to lorries, buses, vans, trains, ships, farm tractors, portable generators.

Electrically driven cars are the future, either pure battery electric, like the VW e-Golf, for local and medium range use, or range extender plug-in hybrids with on-board back-up generators powered by efficient small diesel engines to cope with long trips.