was introduced in the Alfa Romeo Alfa 6 luxury sedan and later used in many other Alfa Romeo models. This engine used a 60 degree V-angle, an all-aluminium construction and two valves per cylinder. A turbocharged version was introduced in 1991 and a four valve per cylinder version was introduced in 1997. Also in 1970, the Citroën SM grand tourer was introduced, powered by a 90-degree V6 built by Maserati. The Chevrolet 90° V6 engine was introduced in 1978 and produced for 36 years. The first mass-produced Japanese V6 engine was the Nissan VG engine, a 60-degree design which was produced from 1983 to 2004. The Honda C engine was introduced in 1985, followed by the Mitsubishi 6G7 engine and the Mazda J engine in 1986, the Toyota VZ engine in 1988, and the Isuzu V engine in 1992. Hyundai introduced the first South Korean Hyundai Sigma engine based on technology shared from the Mitsubishi unit in 1995. German car manufacturers were relatively slow to adopt V6 engines, because engineers believed that they lacked the smoothness of an inline-6 engine. Eventually, the first German V6 engine was a 2.8 liter 90° V6 that was launched in the 1990 Audi 100, and the narrow-angle VR6, which was introduced across Volkswagen's mid-size and sports car lineup in the 1990s. In 1998, Mercedes-Benz introduced the M112, its first V6 engine, while BMW has continued to use inline-6 engines. Mercedes-Benz discontinued its V6 engines in 2017, and has since returned to making inline-6 engines. The first independently designed British V6 engine was the Rover KV6 engine, which replaced the Honda C engine that was previously used in the Rover 800. Jaguar used the Ford-based AJ-V6 engine until 2011 in their smaller cars, but also shared a V6 version of the 90° AJ-V8 engine with Land Rover for use in the XE, XF, XJ, F-Type and the F-Pace. Land Rover used it in the Range Rover, Range Rover Sport, Range Rover Velar, and the Discovery 4. The 90° V6 engine was discontinued in 2020, and Jaguar Land Rover replaced it with the new Ingenium engine, which has an inline-6 variant for JLR's bigger cars and SUVs. By the mid-1990s, the V6 layout was the most common configuration for six-cylinder automotive engines, with V6 engines having replaced most of the straight-six engines. Today, it is being progressively replaced across the car industry by turbocharged 4-cylinder engines,