The flat-six, or boxer engine, is a flat engine with six cylinders arranged horizontally in two banks of three cylinders on each side of a central crankcase. The pistons are mounted to the crankshaft such that opposing pistons move back and forth in opposite directions at the same time, somewhat like a boxing competitor punching their gloves together before a fight, which has led to it being referred to as a boxer engine. The shape of the engine is better for rear engine and mid-engine designs, where the low centre of gravity is an advantage. However, it is an intrinsically expensive design to manufacture, and somewhat too wide for compact automobile engine compartments, which makes it more suitable for luxury sports cars, cruising motorcycles, and aircraft.
The Espresso Veloce Flat Six is a tribute to the last of the air-cooled flat-six engines that were raced competitively during the period 1994 – 1998.