This week, car giant Ford announced a new scrappage scheme for old diesel cars. They’re offering at least £2,000 for the trade in of a pre-2010 motor (any brand) for a new one – as long as it’s made by Ford, obviously.

This is smart PR for the UK’s leading car maker – something that it – and the industry it leads – desperately need. But are scrappage schemes really the answer to the UK’s diesel crisis?

If you’re a car company that makes a lot of diesel cars, you’re a bit hot and bothered right now. The foul stench of the Volkswagen ‘diesel dupe’ scandal still hangs over the automotive sector. Increasingly unbreathable air means that around the world policy-makers are going to war with diesels as we suffer the impacts on our health. Even the UK government, which has been dragged repeatedly through the courts for failing to meet legal limits on air quality, has announced that by 2040 all new petrol and diesel cars will be banned.

Ministers are known to be mulling over a scrappage scheme for old diesels. It last tried this during the economic crisis of 2009, eventually spending £400 million on a stimulus programme for an industry in seriously dire straits. Some economists argued that the scheme only encouraged people to purchase a new car earlier than they would have anyway; environmentalists, meanwhile, bemoaned the lack of ‘green criteria.’ But it did seem to have a bit of an impact, boosting car sales to the tune of about +0.1% of GDP. And a scrappage scheme is also that rare thing – a partial answer to the air pollution problem that looks like quite an attractive offer to diesel drivers.

The problem for car companies is that you can’t wait for a national scheme right now. The industry is flustered, having experienced falling sales for the last four months as purse strings tighten with consumer sentiment darkening. Plus, of course, there’s no guarantee from a national scheme that the new cars people buy will be your new cars. So, reason Ford – and Vauxhall and BMW before them – why not make your own?

How many of us will take up the scheme is up for debate. You still need to fork out a lot for a new car, even with the scrappage discount; you’d probably have had to be right on the cusp of buying a new car anyway.

Yet more is afoot: the reframing of diesel as something that can be not just ‘bad’, but also ‘good’. Some are indeed better than others; those produced to the latest EU standards – ‘Euro VI,’ if you’re keeping score – are in principle much cleaner than those that have gone before. That is, of course, if you assume they actually do in reality what the tests require them to do in the lab.

The writing is on the wall for gasoline-powered cars

What of the environmental case for scrappage schemes? That’s not open and shut. On narrow terms, it’s probably a good thing: the majority of the carbon emissions caused by a standard car used for a normal amount will be caused by its usage, not its manufacture, so a new one may well be a net benefit. It’s more complex than that, of course – new cars need raw materials, and steel, and that kind of thing.

In truth, were you to design a scrappage scheme for purely environmental ends, a-car-for-a-car might not be the limit of your ambition. Proposals have previously been floated to pay people to ditch their wagon and replace it with a season ticket for the railways, or a bike.

Even cleaner diesels are still diesels. They still emit Bad Things that get into our lungs, albeit fewer of them. And while Ford’s official blurb about their plans doesn’t mention NOx, particulates, or air pollution at all but instead the opportunity to purchase a lower CO2 car, diesels are also still fossil fuels. That’s increasingly untenable in a world signed up to radical carbon reduction commitments.

Ultimately, trading in a diesel for another diesel may well seem a little short-sighted. The writing is on the wall for gasoline-powered cars. The fleet is electrifying fast, and autonomous vehicles could rapidly and radically change our perception of what a car even is. Ford is already valued less than electric car pioneers Tesla. As consumers we could risk our new purchase haemorrhaging value as the technology becomes increasingly old-hat. And car companies devoting attention to shifting the gasoline cars on their forecourts might be well advised to get innovating new business models, sharpish.