who informed you?

My X3 has never had any problems pushing 115-120...

If she has an E46 xi, then yes you are correct it has a different drive system. A new E90 however, and it uses the identical xDrive system found in X3's. The difference lies in the fact that the first one, all wheels always have power, with the front getting 40% and the back getting 60% - the only intervention being braking by DSC...