For a high-end luxury sedan like the S-Class to use a flat-plane V8 is highly unusual, primarily because of the engine's characteristics. For a high-end luxury sedan like the S-Class to use a flat-plane V8 is highly unusual, primarily because of the engine's characteristics. It’s why you see 6.2-liter cross-plane V8s and 4.0-liter flat-plane V8s. That means we could, in theory, have something as preposterous as a flat-plane V8 G-Wagen in the future. Still, it’s pretty neat that we live in a reality where an S-Class has a flat-plane V8.