Where did they say that AWD will be 10% less efficient? It could be more efficient, with the three motor system 98% of the time it will be using the single rear motor only. You only need all three motors when getting out of the snow or when flooring it, when you are cruising along a single motor is sufficient.
Sure did, but my recollection of the remark was that the 10 percent decline for adding the rear motor was a first-blush decline in efficiency before, say, power shifting or other approaches to boost efficiency were tried. I.e. with some optimization, the hit for the third motor could be like 3-5 percent.
It is kind of like adding a fourth wheel; the shorthand estimate of the increase in drag and rolling resistance would be 25 % but by placement of the wheel and other strategies, the hit might be as much as 10% lower because of other design efficiencies.