I am trying to giving the service person the opertunity to explain the quote. I have changed a thermostat on a 1997 328iC and that took me about two hours. I am not a trained mechanic working in a shop with proper tools. The location of the thermostat in the 4.4i X5 would lead me to believe that a BMW shop mechanic should be able to change it out in less than 45 minutes.