It is you versus the car dealer and the car dealer has more tricks up his sleeve than you. So how do you go about getting a good deal on that Toyota Yaris for sale when the cards are stacked against you? You have one weapon. You can decide not to buy the car and walk away from the negotiations.
First you need to do a little research on prices for similar models with similar mileages and in similar conditions. Of course before you can do that you need to be aware of the condition of the car. If the dealer has not informed you of any potential problems with it after you have asked him that question, and if there are no obvious problems with it that you would normally detect, then at least you are protected by law should any problems manifest themselves in such a way that the vehicle becomes not fit for purpose or not as described; either way you are entitled to a refund if the car cannot be fixed. In other words you can safely assume that the car is as it appears to be.
The main tip is not to get fixated on any particular car. The BMW with which you have fallen in love and must have is probably little different from the one down the road. It is better to negotiate with several dealers simultaneously and play one off against the other. The ‘walk away’ trick may be a bit of a cliché, but it is one that still works quite successfully.
It is often said that buying a car at the end of the month when the dealer needs to make up his quota is a good time to get a good deal, though how many dealers have said “I must make up my quota so I will sell this car to you at what is a loss to me”, and how many buyers have believed him?