When viewing a vehicle you'll see 'Competitors' in the left sidebar. This feature requires a connected AutoTrader account and therefore the link will not be shown if an account is not connected.
This section allows you to browse other competitor adverts for the same make and model of vehicle on AutoTrader, including photos of the vehicles, the prices they list them at and the optional extras they offer.
The manufacturer and model will be completed automatically and can not be changed, but you can adjust the vehicle trim. You can then choose the parameters of your comparison search, such as the engine size and mileage range, how many doors the vehicle has.
Once you set the parameters you'd like to search click 'Search' and it will bring up the results from AutoTrader for you - showing every competing advert within the selected radius allowing you to research vehicles both locally and nationally.
At the top of the results you'll see an average price, average valuation, average amount of days taken to sell, and distance radius from your dealership.
Below this is a full comparison of all the competitor listings. You can rearrange the order of the list by clicking any of the column headers and you can scroll across to the right to reveal more statistics. If you scroll across to 'Options' you can see what optional extras the vehicles may have to help understand differences in price and valuation. You can also see how many have a 'Full Dealership History' and how many days they've been on the forecourt.
At the very bottom you have a useful visual aid for these comparisons. You can select a range of different variables for the X & Y axis. Competitor vehicles will show in blue and your vehicle will show in light blue. It can show you useful comparisons like how your listing price ranks against other vehicles from the same year or the mileage of your vehicle compared to vehicles of a similar price. These charts can give you good indicators of how you should be pricing your vehicle in the market.