The new BMW M5 will do zero to sixty in 3.4 seconds. It weighs 2,445 kilograms. These two facts exist in a tension that the M division has spent considerable engineering effort resolving and that no amount of engineering can fully reconcile. The car is extraordinarily fast. It is also extraordinarily heavy, and the M5 lineage — from the E28 original through the E39 that most enthusiasts consider the definition of the breed — was built on the proposition that performance and mass should not coexist if the goal is driver engagement.