Autotrader Shows Used Petrol Cars Cost £14,625 as 17 Months of Price Rises End

• Autotrader’s Retail Price Index puts the average used car asking price at £17,299 in September 2026, with like-for-like prices down 1.0 percent on a year earlier and 0.8 percent on August.
• The average petrol car costs £14,625, down 1 percent and the end of 17 months of annual rises, while diesel is £13,924 and used electric cars are £25,091, up 2.8 percent.
• Cars aged 10 to 15 years rose 5.6 percent to £7,144 on average, while models such as the Nissan Ariya fell 17.9 percent to £23,146.

The price of a used petrol car has stopped climbing for the first time in a year and a half. Autotrader’s Retail Price Index for September 2026, published on 9 October, puts the average petrol car at £14,625. That is 1 percent below the same month last year and ends 17 consecutive months of annual growth. Diesel is cheaper again at £13,924, down 0.8 percent, and the overall average asking price across all fuels is £17,299.

For anyone buying a used car this autumn, the headline movement is small in pounds but the direction is clear: prices are flat to falling for most petrol, diesel and nearly new cars, and rising only for used electric cars and for very old ones. The index also names the individual models whose prices have moved furthest, which is where the biggest sums sit.

Buyers of 10-Year-Old Cars Now Pay £7,144 While Nearly New Cars Get Cheaper

Autotrader publishes its Retail Price Index monthly, using like-for-like comparisons of the cars listed on its platform. The September release covers asking prices across the whole UK market. Autotrader reports that average days to sell stood at 29, the same as a year earlier and one day faster than August.

The split by age is where the story sits. Autotrader’s like-for-like figures for September, compared with September 2025, are:

• Cars under one year old: down 2.7 percent.
• Cars aged one to three years: down 2.4 percent.
• Cars aged three to five years: down 1.0 percent.
• Cars aged 10 to 15 years: up 5.6 percent, to an average of £7,144.

The pattern runs in opposite directions. The newer the car, the more its price is falling; the older the car, the more it costs compared with a year ago. A driver buying a 10 to 15 year old car is paying 5.6 percent more than a year ago, while a driver buying a car under three years old is paying around 2.5 percent less.

Compared with the previous release, the older-car climb is slowing. Autotrader’s August 2026 index, published on 8 September, had 10 to 15 year old cars at £7,183, up 6.9 percent on a year earlier. The September average of £7,144 is £39 lower and the annual rise is 1.3 percentage points smaller (our calculation). The one to three year band has weakened over the same month, from down 1.8 percent in August to down 2.4 percent in September.

Petrol, diesel and electric: a £701 gap and a £10,466 premium

Autotrader’s fuel-type averages for September 2026 are:

• Used electric cars: £25,091, up 2.8 percent on a year earlier. This is the fifth month in a row of like-for-like growth and the only fuel type with annual price growth.
• Used petrol cars: £14,625, down 1 percent. Autotrader says this ends 17 months of annual growth. Demand fell 5.8 percent and supply fell 5.7 percent.
• Used diesel cars: £13,924, down 0.8 percent. Demand fell 19.2 percent while supply fell only 6.8 percent.

On those averages, a used petrol car costs £701 more than a used diesel one, and a used electric car costs £10,466 more than a used petrol one (our calculations from Autotrader’s figures; the cars in each group differ in age and type, so these are market gaps, not like-for-like comparisons).

The electric figure comes with a supply story. Autotrader reports that demand for used electric cars is up 40 percent on a year earlier, against supply up 26.0 percent. Marc Palmer, Autotrader’s head of strategy, said: “Demand for electric cars is comfortably outpacing supply, supporting continued price growth.” Petrol and electric cars both averaged 28 days to sell.

The overall average asking price of £17,299 is £168 higher than the £17,131 in the August release (our calculation). That is a shift in the mix of cars listed, not a rise in prices: Autotrader’s like-for-like measure, which tracks the same kinds of car, fell 0.8 percent on the month. In August that month-on-month figure was down 0.4 percent, so the monthly slide has widened.

The models falling fastest: up to £44,037 and down 15.6 percent

Autotrader also lists the ten models with the biggest annual price falls across all fuel types. Average asking prices in September 2026, with the change on September 2025, are:

• Nissan Ariya: £23,146, down 17.9 percent.
• BMW i5: £44,037, down 15.6 percent.
• Jaguar E-Pace: £14,747, down 15.4 percent.
• Peugeot 408: £17,963, down 15.0 percent.
• Vauxhall Grandland: £16,934, down 14.9 percent.
• Mazda MX-30: £12,409, down 14.1 percent.
• Vauxhall Mokka X: £7,430, down 13.7 percent.
• Ford Edge: £12,396, down 13.1 percent.
• Vauxhall Crossland X: £7,451, down 12.0 percent.
• Volvo S90: £14,884, down 11.5 percent.

The Nissan Ariya and BMW i5 were also in the August release’s list of biggest fallers. The Ariya was £23,419 and down 17.3 percent then, so it is £273 cheaper in a month, and the i5 was £44,198 and down 15.3 percent, so it is £161 cheaper (our calculations). Both are still sliding.

At the other end, the ten models with the biggest annual price rises include the Porsche Boxster at £22,063 (up 21.6 percent), the Renault Zoe at £9,225 (up 15.2 percent), the Mazda MX-5 at £12,821 (up 11.0 percent), the MG5 at £11,494 (up 10.9 percent) and the Skoda Enyaq at £25,884 (up 10.5 percent). The Boxster is £1,141 dearer than in the August release and the Zoe £330 dearer, while the Enyaq is £332 cheaper but still up 10.5 percent on the year (our calculations).

Can You Avoid Paying More for a Used Car?

Nobody sets these prices for you, but the index shows where buyers hold the stronger hand and where they do not. These are the practical steps the data points to.

Look at one to three year old cars before a new one. Prices for cars under one year old are down 2.7 percent and for one to three year old cars down 2.4 percent, the two steepest falls in the index. A buyer in this band is paying less than a year ago for a car with most of its life ahead, and the August to September slide suggests the trend has not stopped.

Be wary of the 10 to 15 year band. This is the only age group the index shows rising sharply, at 5.6 percent to £7,144. A three to five year old car is falling in price at 1.0 percent. If your budget is around £7,000, compare what the three to five year old market offers against the older cars before you commit.

Use the diesel and petrol gap. Diesel demand is down 19.2 percent while supply is down just 6.8 percent, so dealers have more diesel stock to shift than buyers to take it. That favours a buyer who is happy with a diesel car and is ready to haggle, though running costs are a separate calculation from the purchase price.

Do not expect a discount on a used electric car. With demand up 40 percent and supply up 26.0 percent, sellers hold the upper hand and the average is £25,091. The exceptions are the individual models in the fallers list. A Nissan Ariya at £23,146 or a Mazda MX-30 at £12,409 is cheaper by double-digit percentages than a year ago, so a seller asking last year’s price is out of step with the market.

Check the advert against the market before you phone. The averages above give you a yardstick. If a seller is asking £1,500 over the current average for the same model, age and mileage, that is a reason to ask why or walk away. With 29 days the average time to sell, a car sitting for longer than a month is one where the seller has already seen little interest at that price.

If you are selling, the older end is where the money is. A 10 to 15 year old car is worth 5.6 percent more than a year ago. Newer cars are the reverse: if you own a nearly new car you plan to sell, September’s figures show values still slipping, at 2.7 percent a year for the youngest group.

All of the figures above are asking prices, not the final amounts paid, and Autotrader’s averages mix many different cars. Treat them as a guide to direction and to the models moving fastest, and check any specific car against several current adverts before you agree a price.

Sources

• Autotrader: Used EV demand surges 40% as rising fuel costs reshape used car market (Retail Price Index, September 2026 data, published 9 October 2026)
• Autotrader: Used car market gains momentum as both independent & franchise retailers record growth for first time this year (Retail Price Index, August 2026 data, published 8 September 2026)