From 1991 onwards Volkswagen (including Audi) have used narrow-angle Vee engines, originally VR6s. The concept is to set the cylinders at 15°, which is close enough for two banks to share the same cylinder head. Later they began to mount two VR6s on the same cases, making a “W12” which is astonishingly compact, and they have made VR5 and W16 versions too. Now that Ducati is part of VW Audi, how about this for an idea? They could make a “W4”, consisting of one vertical block and head with two cylinders 15° apart, and another horizontal block and head (90° away) with another two cylinders 15° apart, all mounted on the same crankcase. The whole engine would be about the same shape and size as a 90° V-twin, but slightly more compact. It would be a way for Ducati to create a unique four without losing the special advantages of their twins, while fitting into the VW way of doing things. Matchless made narrow-angle Vtwin and Vfour engines in the 1930s and Horex is about to introduce a brand new 1200 VR6 motorbike, so the idea is by no means off the wall.
