The M118 is a four-stroke inline-four engine produced from 1965 to 1972.
Design
The M118 was originally developed by Mercedes-Benz for the mass-produced vehicle segment. It was first used by Audi in the F103, after Daimler AG sold the company to Volkswagen. The engine replaced the previous two-stroke engines, featured a Solex carburetor, and utilised a swirling effect in the intake ducts that allowed for smoother operation and enhanced efficiency. It was later revised several times with increased displacements and reduced compression ratios for improved reliability. The success of the M118 allowed Audi to expand into more upscale market segments.