Very true Lorz, but I found big differences in how much you can get off, depending on what part of the country your in.
For example: I was looking for either a BMW 320d estate or Audi a4 tdi estate about the 2001 / 2003 age
I’m in Cork, so I tried my local Dealers, who didn't want to know when I started haggling hard.
Then I tried different parts of the country and settled on Wexford where I bought my car. It was a long bus journey over there, but worth it in the end. Plus the car comes with warranty that can be used in the above Cork dealers Garage! Handy.
The above is also true for New Cars - shop around