Toyota unveiled the Mark X sedan in 2004 as the successor to the Mark II sedan which has been on the market since the late 1960s. Instead of being based on a modified Supra chassis "A" series platform, the Mark X continues to use the Toyota "X" platform, and does not share its platform with the Toyota "S" series platform used under the Crown and Lexus GS. The continuation of describing this vehicle as the "X" series is a reference to the first dedicated Mark II platform introduced in 1972. Major changes to the Mark series are the engine and footwork. Toyota discontinued the inline-six engines used in the Verossa which included the JZ series and the G series engines, and went to the newly developed GR series engine. Either the 2.5 L (2,497 cc) "4GR-FSE" or the 3.0 L (2,995 cc) "3GR-FSE" engine options were available.