Chris_D...you really need to watch the test, as there is a comparison to 'control winter' and an accidental winter in the line up.
Even in full winter conditions, some of the all-seasons out-perform the full winter in some tests.
The biggest downside for me running an all-season all year round on the Z4, is that I'd want a bigger sidewall on a winter to help with unseen potholes and debris on the roads, and of course one wheel/tyre combo all year round will never be able to offer that!
On the Z4 I use a summer tyre all year round, but it rarely sees snow and has never become stuck...partly due to luck, partly due to skill, and partly due to looking out the window and deciding to take a different vehicle.
On the Alfa diesel I ran Cross-Climates all year round and took that on a couple of track days & Ring trips where the weather was looking poor. However it also helped out when there were a series of closures as I found a farm track through the woods where the Z4 would never make it, but the Alfa on CCs climbed up and over the hill, through the mud and over the fallen branches.
That was on gen 1 Cross-Climates, we're now on gen 3 (albeit called Cross-Climate 2 as there was a Cross-Climate Plus in between)...and the tests show they've improved in all areas...although I didn't see a muddy woody hill climb test in there
