October’s fuel cap price increase - if implemented - would result in a safety risk for motorists as one-in-five say they plan to cut back on car maintenance.

According to September’s Startline Used Car Tracker, 77% also believe the rise in gas and electricity prices would impact on whether they could afford their car, with 18% putting off replacing tyres and 22% delaying having their vehicle serviced.

Other measures that those questioned would adopt to cut motoring costs include shopping around for cheaper fuel (47%), using their car less (42%), swapping their car for one that is more economical to run (34%) and finding a cheaper place to have their car serviced (12%).

Paul Burgess, chief executive officer at Startline Motor Finance, said: “The research shows the huge pressure that the fuel cap increase would bring to bear on personal finances, and how it is likely to affect whether people can afford to simply keep their cars safe.

“Petrol and diesel prices are starting to fall, so there is an opportunity to make savings there, but it is interesting that more than a third of people are looking to change their car for one with lower costs.

“That suggests we could see increased activity in the used car sector in the final quarter of the year. Also, if people plan to move into more economical cars, higher demand will inevitably drive up the price for these vehicles.”

Startline’s September research also suggests the used car market remains in a relatively stable position. When asked whether used cars were more attractive purchases than new, 73% of people agreed, while the number of people who say they are likely to buy a used car remains high at 63%.

While 7% of respondents believe that used cars have become more unattractive purchases, 71% of those people say that used car prices are a concern compared to 14% who were asked the same question in July.

Suggestions that the UK’s used car values are in steep decline and on the verge of a crash have been slammed as “sensationalist speculation” by Auto Trader.

The average marketing price of used cars remained flat in August as stock volumes continued to dip and days to sell improved, according to the latest eBay Motors Group Market View.

Burgess added: “The used car sector remains buoyant and has been remarkably resistant to falls in consumer confidence over the last few months. Much of this is down to the fact that vehicles remain in such short supply, with demand still strong in most parts of the market.

“Despite this positive picture, there are some signs that a group of people are beginning to be priced out of the market, with growing concern among a small minority about pricing.

"For most of this year, used car prices have been stable and even fallen slightly, so the obvious conclusion is that they are simply no longer able to buy because their personal finances have worsened.”

Startline said there has been a marked increase in those who trust petrol and diesel technology - from 44% to 52% - and a decrease in those saying electric cars are too expensive - from 49% to 38%.

Burgess said: “There are a couple of different trends here. One is that petrol and diesel potentially look like a safe haven for people who feel that their personal finances are under threat. They are tried and trusted.

“The other is that the increase in fuel prices that we have seen this year might have caused people to rethink the economics of electric cars. Although they are expensive to buy, charging and maintaining them can be very cost-effective.”