They are the same in that an E91 328xi Touring and an E92 M3 Coupe are the same car.

I think it's a bit silly to argue that two cars are the "same" because they share some of the same mechanical components. If, for example, two cars share the same frame (like Nick's comment about the M3 and the 328) - but are tuned, equipped, and priced completely differently - they're hardly the same in any comparitive sense.

But to argue that the 911 and Beetle are the "same" because they both mount the engine over the rear wheels is like saying a covered wagon and a Chevy Suburban are the same because they both hold a lot of stuff and frequently travel the plains...it's just silly.