Myself & Jon D have commented on this many times
I can't see a software correction helping - the whole point of the Efficient Dynamics Electric Power Steering is that it's off at motorway speeds.
I'm of the opinion that the geometry has been set to minimise rolling resistance and this is the issue. Not enough caster (?)
Current: 2013 F10 520d M-Sport, Professional Media, Visibility Pack, Reversing Camera, DAB
Previous: 2011 F10 520d M-Sport, 2008 320i M-Sport Coupe, 2002 325i, 2001 318i valvetronic, 1998 318i, 1996 525i, 1990 Porsche 944S2