Audi is working on a totally new type of four-cylinder engine that is intended to be as smooth running as a six-cylinder or eight-cylinder unit.
The move comes as premium car makers embark on a big reduction in the fuel consumption of larger models - such as the A8 L - by downsizing engines and using hybrid drivetrains.
It’s thought that Audi was awarded a patent for this unusual design last year. The description is for an “internal combustion engine with multi joint crank drive and additional masses on articulated connecting rods for damping free inertia forces.”
In simple terms, this design uses a radically different layout to avoid generating the internal forces that make four-pot engines less smooth.
The pistons and conrods no longer run in line with the crankshaft. Instead, they are offset to one side of the crank and connected to it via a rocker-style link.
The centre of the rocker link is attached to the crank and the other end to a second conrod, which is attached to a fixed shaft and has a counterweight at its head.