The partnership will extend sales opportunities for Auto Trader's retailer partners by reaching a further 24.9 million consumers each year.

Buyers looking at used cars on each site will now be brought onto Auto Trader’s marketplace, which currently features nearly 440,000 used vehicles.

Auto Trader will also be the editorial sponsor for used-car reviews and feature articles, all of which will include Auto Trader branding to help drive further awareness among What Car?’s and Autocar’s respective audiences.

Rachael Prasher, managing director at Haymarket Automotive, publisher of Autocar and What Car?, said: “This is a brilliant partnership between two of Britain’s biggest and best-known car-buying brands.

“Visitors arrive on the What Car? website at every stage of their car-buying journey, from their earliest research to when they’re ready to buy, and the opportunity to connect our class-leading used-review visitors to the biggest used-car-buying marketplace makes perfect sense."

Auto Trader COO Catherine Faiers added: “We’ve long been an admirer of What Car?, which has a heritage as long and as rich as our own, with both brands synonymous with the UK automotive-retail sector.

“At a time when the industry is facing new challenges, this partnership gives us an exciting opportunity to bring new buyers onto our marketplace much earlier in their journey, and in front of our retailer partners’ stock.