I have the same gripe - here's the post I made in another forum today:
Ok, I really love the heads up display and don't think I can live without it again, BUT... The HUD in the 2013 335xi is better, and I'd love to know why they aren't the same. Here are my "suggestions" to anyone from BMW who monitors the forum.
In the 335, the speed, navigation, radio scrolling, music choices, incoming phone ID - everything - is shown in the HUD. I never need to take my eyes off the road and can do all choices with my thumb on the wheel. In the X3, only the speed and navigation are shown. Radio and phone functions (anything that operates from the thumb wheel) are shown down in the instrument cluster - this is a poor location (have to look all the way down and refocus), and it duplicates the info on the control screen which is actually higher and larger font. The thumb wheel on the steering wheel is almost never used because it's easier and safer to use the control screen and the iDrive knob.
The less important item is that in the 335 the HUD speed is white during the daytime and orange at night - in the X3 it is always orange. Does anyone know why they made the decision to make them different? Is there some secret switch I'm unaware of that would make the X3 as good as the 335? And can it be coded to act the same?