Ok i know its been - 2 and -3 out there, but i have found the heaters aren't the best in the world, ( and i have driver a LOT of Range Rovers more than most) and they always seem to be that way in very cold whether, they just about manage in very cold weather, also there is a lot of glass in them for the heat to escape, and if you smoke (im giving up this year!!) and you crack the window open that wont help, ever noticed how they improve as you go around a bend or corner for a few seconds??