I thought most of the TomTom units (except the ONE series) use the same hardware (CPU, RAM, etc wise). Why is it that the TomTom x20 and later units, with their 1300mAh batteries, lasts 5 hours where the x10 units, with a 2300mAh battery, lasts only 4 hours? Even with newer hardware, I don't expect it to reduce power consumption by half, since I believe the screen uses the most power by far.