Scrappage schemes are suddenly all the rage, unless you are Vauxhall, which has had one running for months but without pinning it to any emissions-reducing fanfare.

This month, however, BMW, Mercedes and Ford jumped in and now Volkswagen, Audi, Seat, Skoda and plenty more have followed suit. Each scheme has different terms and conditions - of which more later - and each is laudable in some respects of the stated environmental goals, but how much difference do we really expect them to make?

Let’s start with the upsides; vehicle emissions have been pretty hot news since the VW scandal broke two years ago and - finally - these schemes are turning the tide of negative headlines and allowing the car industry to broadcast that modern engines are relatively pretty clean.

​Here are some stats from Ford:

- Diesels from 1993 produce 82% more CO (carbon monoxide) on average than today.

- Petrols from 1993 produce 63% more CO (carbon monoxide) on average than today.

- Petrols from 2001 produce 50% more HC (hydrocarbons) on average than today.