To my mind, the problem that the RAC faces is not one of volume of cars advertised, but of brand. Whilst I accept that the RAC is a well known 'household brand', it is not known for advertising cars for sale. Whilst a high number of vehicles listed for sale will undoubtedly help its organic Google rankings, it would need to spend millions on TV advertising over (at least) a 3 year period to enter the public's consciousness. Just look at what motors.co.uk has spent. That said, Auto Trader's biggest enemy is itself - it has a lethal combination of complacency and greed. Its business model surely relies on people ONLY looking at the Auto Trader website for their next car. As the number of cars advertised by Auto Trader starts to fall and the number advertised by their competitors increase, more and more consumers will look at other sites to find the car they want. I firmly believe that only a small number of customers would look only on the Auto Trader website for their next car. I know if I am looking to make a major purchase, be it a fridge or a house, I would not look only at Curry's or the Rightmove website. So the task in hand for any competitor to Auto Trader is that of awareness.