Your Mileage May Vary

So a buddy of mine picked up a used car like mine with 26k miles on it.  I've put 4k miles on mine so far.  I've averaged 44.6mpg lifetime and over 46mpg the last two tanks as the engine has gotten more broken-in.  The lady who owned the car my buddy bought was only doing 37mpg.  It just goes to show, driving technique is everything when it comes to mileage.  20% difference is no joke.