Motorists are overwhelmingly planning to abandon diesel in favour of petrol, hybrid and electric powered cars.
The move will come in response to inner-city emissions charges and the prospect of higher taxes.
New research reveals that three out of five current diesel owners intend to choose a different fuel type, next time they change their car.
It also means a boost for hybrid and electric cars, with a quarter of current diesel car owners planning to switch one of those options.
The figures come from a survey of almost 1,000 motorists conducted in April by the specialist online motor retailer BuyaCar.co.uk.
Almost half of those drivers currently own a diesel car.
Owners said that the prospect of emissions charges was the main reason for planning a change in their next engine type.
A recent government consultation report suggested that strict measures to curb diesel-related emissions could be imposed in around 27 UK towns and cities.
As well as future financial concerns BuyaCar.co.uk’s research also reveals a trust gap between customers and manufacturers around official emissions data, in the wake of several scandals in which some car makers have been accused of fiddling their testing figures.
Almost one in three diesel drivers who are planning to change to a different type of car told BuyaCar.co.uk that they do not believe all manufacturers’ emissions claims.
“We’re already seeing sales of petrol, hybrid and electric cars increasing at the expense of market share for diesel,” said Austin Collins, managing director of BuyaCar.co.uk.
“That’s only going to increase as we hear more about the government’s plans. We’ve even had buyers changing orders they’ve already placed with us and choosing a non-diesel car instead, because of something that they heard on that morning’s news.”
BuyaCar.co.uk polled 1,000 drivers, of which 48% owned a diesel car. Just 40% of those existing diesel drivers said that they planned to buy another diesel when the time comes to change their car.
Of those who say they will change engine type, 35% say they will go for a petrol model while 20% are looking into hybrid cars and 5% are interested in switching to an electric vehicle.
Drivers who plan to desert diesel typically cited the prospect of future charges but almost half of them said they were also concerned about the environmental effects of diesels on air quality.
The Volkswagen ‘dieselgate’ scandal appears to be having a lingering impact on trust, with 30% saying that mistrust of official testing figures has played a part in their decision to switch.
Other comments BuyaCar.co.uk received during the research also revealed improved perceptions of petrol cars among many motorists. They typically cited improvements in petrol car fuel economy, perceptions that petrol cars are smoother and quieter, lower purchase costs and fewer expensive problems when things go wrong.
But a belief that diesels are set to become prohibitively expensive to run was the dominant theme, even though many modern examples will actually escape the worst of the forthcoming anti-pollution penalties.
“Owners of newer diesel cars, built since September 2015, had to pass tougher emissions tests so they are less likely to be impacted by some charges,” said Collins.
“But petrol cars are cheaper and increasingly economical, and hybrid or electric cars even more so. And it is those factors that are tempting people away from diesel next time they change their car.”