S63

The S63 shares the N63's notorious oil consumption problem rooted in the hot-vee layout. Valve stem seals degrade prematurely due to extreme heat from the turbos sitting inside the V. This led to a class-action lawsuit against BMW. Dealers replaced piston rings under extended warranty but consumption often persisted. Some owners report losing 1L per 200–1,000 km.

The hot-vee design places both turbochargers inside the engine V, exposing them to extreme radiant heat. This accelerates turbo bearing wear and can cause oil coking in turbo feed lines if oil changes are neglected or if the engine is shut down immediately after hard use.

EGR cooler cracking and leaking is a documented issue on BMW V8 engines of this era. A cracked cooler can introduce coolant into the intake or cause coolant loss, potentially leading to overheating if undetected.

The oil cooler seals and coolant valley pan located deep in the engine V are prone to leaking due to sustained high operating temperatures. Access requires significant disassembly, making labour costs the dominant expense.

The stock intercoolers on the S63 are known to become a limiting factor, especially if the car is used on track or driven hard. Heat soak reduces charge cooling efficiency, leading to power loss and increased knock.

Beyond specific failures, routine maintenance on the S63 is expensive due to its complexity. Spark plugs, fuel injectors, belts, and ancillaries all require specialist access and carry premium part costs.