Also, the A8 is lighter than the A6 and based on the commentary and drawing of the upcoming A10, it's not even that much different in terms of exterior design and probably only modestly heavier due to a few extra shift elements
http://gmauthority.com/blog/2015/01/...#ixzz436NIi6Cy
So, from what I've seen, I don't think the A10 will have a serious weight penalty like autos of the past.... I would think the bulk of the Z's weight will be in the other areas of the car that will be present in both stick and auto (e.g. - beefy shafts, axles, etc.)