I think it depends on the dealer really, their stock, pricing policy etc - if you search carzone for example, you will find the same cars that range in price by 30% easily, so if you have already narrowed your search to the lowest priced within the range, then you will not get 25% off, but if you are looking at ones that are in the upper range, then you have more bargaining power, and can point out there are other dealers selling similar cheaper. Friend of mine bought a car for 9K recently, that was advertised at 12K - but there were other similar cars, same make, model, spec, mileage etc. that were advertised at 10K or so.