Although the S6 has slightly less front leg room than the BMW 540i and Mercedes-AMG E 53, that's a bit like saying the Asian elephant is smaller than the African; the point is that both are big old beasts.
But the S6’s rear leg room is particularly impressive, beating both its key rivals for space in the back. Plus, accommodation for three adults sitting side by side is more generous, even though the middle passenger has to straddle a hump in the floor.
Those rear seats split and fold 40/20/40, but even with them in place we fitted nine carry-on suitcases in the boot of the saloon. The Avant estate, meanwhile, is obviously even more accommodating, and its tailgate and luggage cover open electrically. However, for the ultimate in load-lugging ability, you’ll need the Mercedes E 53 Estate.