Online car marketplace BuyaCar will offer vehicles up to six years old in response to customer demand for more choice.
The company has previously only sold new or nearly-new cars but now believes consumers are more confident to buy older vehicles sight unseen.
It says the move will enable many more buyers to acquire brands that were previously out of reach among the site's current stock of 70,000 vehicles.
Peter Gibney, commercial operations manager of BuyaCar.co.uk, said: "A car purchase is a big step for most people and those who are buying a car for £5,000 are just as demanding when it comes to quality as anyone paying £25,000 or more. That makes it vitally important to manage buyers' expectations fairly and transparently.
"But we are also aware that this is a maturing market and consumers are increasingly sophisticated when it comes to buying cars online. That is why new names, such as Cazoo, are appearing in online motor retail and we are determined to maintain the widest possible choice as well as a frictionless buying experience to consumers as this market continues to grow."
In 2019 cars at five years represented the second most popular age band for sales on BuyaCar.co.uk, suggesting that some of the strongest demand from online car buyers is at the budget end of the market.
For example, those who aspire to a Mercedes are now able to buy a 14-plate A180 CDI Sport, with 40,000 miles for the same price as an 18-plate Ford Focus 1.5 TDCi 120 Zetec with 14,000 miles.
Online car-sellers have previously been reluctant to offer older stock due to the challenge of managing customer expectations around the quality of the vehicle. While an older car can be mechanically sound and in very clean condition, signs of wear are inevitable in older vehicles. This presents a risk of disappointment due to unrealistic expectations that a five or six-year-old car will be in identical condition to a much newer one.
BuyaCar.co.uk has addressed this in an initial pilot of 2,000 six-year-old cars by implementing a rigorous condition report which the original supplying dealer must provide to BuyaCar before the site will commit to offering a car for sale. In turn this detailed information on any age-related aspect of the car, such as minor signs of wear, enable the business to describe the condition of an older car with 100% transparency, during the sales administration process.