Originally Posted by Brad from the OC
If you have an older model and have the REST feature, you can enable the ALL function without coding or other highly technical patches. I simply just join the two temperature control knobs together with a rubber band. With this simple fix, you have both the ALL capabilities and the REST feature also!
But why is everybody so worried about the two temperatures? BMW allows you the option for two different temperatures on purpose! If you drive long distances, for example, you'll notice that your passenger typically is cold sooner than you. You are actually "exercising", therefore are "warmer" then the passenger who simply sits still. Me and my girlfriend typically have 2 degrees F difference between ourselves.
When she gets in, and uses her set of keys, the temperatures change to her preferred setting (and so does the seat and mirrors).
Anyway, my point is: why don't you leave the setting of the passenger to a different temperature? You're not sitting there! You're side has your temperature. Why worry about a passenger that is not there?