Dealers’ used car transaction prices vary significantly between different regions of the UK for similar models in terms of brand, specification, age and mileage, according to figures from Autovista.

Take the two extremes in the table – London and the south west.

Prices of three-year-old cars are on average some nine points higher in the south west, compared to the capital.

Why? It’s all about population.

The south west is more isolated and less densely populated with a lower sales volume. As a result, its people are more likely to buy cars from local dealers so the prices stay higher.

In London, however, more people are searching online for prices and are happier to travel further afield to buy cars based on the best price.

That forces down the average price in the local market.

As the age of cars rises, it makes less economic sense to search further distances for the best price.

Therefore, the London line in the graph rises substantially for cars up to six years old, moving much closer to the national average.

The strength of groups also has an impact.

In areas where there are very strong regional groups, prices will tend to be higher because they have more control over the local marketplace.

The most notable findings at the beginning of August are that prices of used cars are clearly more expensive in south west England than the UK average.

On average, the prices of a six-year-old used car with 60,000 miles on the clock in the south-west is 4% higher than the average price level of similar cars in the UK.