This is no longer a common configuration, but some brands of automobiles use such engines and it is a common configuration for smaller aircraft engines such as those made by Lycoming, Continental and Rotax. Although they are superior to straight fours in terms of secondary vibration, they have largely fallen out of favour for overhead cam design engines, for which an opposed-four cylinder layout would require twice as many camshafts as a straight-four while the crankshaft is as complex to manufacture. The low centre of gravity of the engine is an advantage.