though you don't tell us which x5 you have, you may be operating the heater wrong as well. our hvac system works like our house. we set it at 70 and leave it there. the X5 decides when to turn on or off to regulate the temperature to this level.

as well, when first starting out, the x5 is smart enough to have the fan on low until the engine is warm enough to deliver warm air. no use having a high fan speed only to increase the windchill. if your friends regularly do this, just reach over and punch them