New diesel cars will be banned from sale by 2040 but, before then, they face the threat of toxicity charges, diversions away from the most polluted roads, extra fuel duty and parking surcharges - all in the coming few years.
It's no surprise that sales of new diesel cars plunged by 15% last month. There's little sign of that trend being reversed, as three in five drivers who currently own a diesel plan to change it for a petrol, hybrid or electric model, according to a recent survey. The majority of those said that they wanted to avoid future diesel charges.
For some drivers, it will be best to buy a non-diesel car and stop worrying. But as buyers avoid the cars, used diesel vehicles are dropping in value faster than petrol models. And as they become cheaper, some consumers may find that diesel makes more sense than ever - particularly when bought on finance, which can protect against an unexpectedly high loss of value.
If you do buy a diesel car, then the chances are that you won't be eligible for any diesel scrappage scheme. If these are launched, then they are likely to be offered to owners of old vehicles, in a few of the most polluted areas
Read on to find out whether diesel is right for you. Scroll futher down the page for our diesel car buying advice, including how to avoid future charges when buying a used car.
Many modern diesel cars are fitted with a diesel particulate filter (DPF), which can clog if you don't often drive at motorway speeds. It's a pricey fix, so best avoid diesels if you avoid motorways. Diesel cars tend to cost more to buy than an equivalent petrol car. In the past, it was possible to make this back thanks to diesel cars having lower car tax and fuel costs.
Since the new car-tax change, from the second year of ownership you'll pay a standard rate of £140 a year. This means it will take you longer to recoup the higher on-the-road price you pay for a diesel car, as you will now only save between £105 to £125 on running costs per year (largely thanks to better fuel economy). Diesel cars also tend to be the fuel of choice for those who need to tow thanks to diesel engines producing huge amounts of torque (pulling power) - but petrol and hybrid alternatives are available.
Diesel cars tend to have better fuel economy. So, despite diesel fuel typically costing slightly more than petrol (by 1p to 2p a litre), a diesel car's fuel costs will be cheaper than the equivalent petrol car. Our unique Which? tests show that, on average, diesel cars are more efficient by about 8mpg (based on tests of 249 cars that all meet the latest emission limits: Euro 6). That doesn't sound like much, but can save you around £200 a year.
You can reduce the risk of being hit with inner-city diesel charges by buying a newer diesel car that complies with the latest emissions regulations, called Euro 6. In London, these vehicles will not be subject to any planned emissions charges. Current indications are that they will also be exempt from charges in up to 27 other cities which could set up clean air zones.
Every car registered since September 2015 is required to meet the Euro 6 standard, and many complied earlier (see below).
If taxes rise for diesel vehicles or the fuel, then there's unlikely to be any escape, no matter what their age. The Chancellor has said that an increase is being considered for this autumn's Budget but the Prime Minister has implied that the government will not come down hard on motorists, given that the previous car tax regime effectively encouraged drivers to buy diesels.
In the longer-term, London plans to introduce a zero-emission zone in 2025. This is expected to ban petrol and diesel cars from the very centre of the city, and gradually expand until it covers all of the capital in 2050.