I love Inline-6s. Torquey due to a relatively longer stroke, and smooth due to a very high level of engine balance. They're great in cars (BMW E46 3.2l M3, Ford 4.0l XR6T), but it's a while since they've been used in motorcycles. I think the last production inline-6s were the 1978-82 Honda CBX-1000 and 1979-89 Kawasaki Z1300. Suzuki recently made a concept called the Stratosphere, and Honda have developed a naked utilising the 1800cc Goldwing Flat-6. Now that BMW have announced their Concept 6, hopefully enough interest and momentum has been generated for one of them to actually reach production!! Previous NetRider discussion on 6 cylinder motorcycles here.