American market cars had the 2.3-litre M-series "six" when they first went on sale in early 1972, but in August of that year this was replaced by the larger 2.6-litre 4M unit. Power, originally at , increased to . This was the only engine offered for the Mark II's next four years in the North American markets. Third generation: Toyota Mark II (X30, X40; 1976–1980) The third generation was introduced with a more upscale, European type design. The lines are a combination of the previous generation's American styling with a British-looking front end, while demonstrating a new corporate Toyota appearance with the larger S80 series Crown. This model generation was amongst the last cars to feature the Toyopet brand name, which was dropped in 1980. The Toyopet name continued to be used for the dealership network in Japan, however. The Grande trim was added to models with six-cylinder engines. This generation continued to offer Japanese buyers an alternative to the Nissan Laurel sedan, and the new Nissan Bluebird based Nissan Maxima in North America, with the new Chaser as an alternative to the Nissan Skyline in Japan. The Mark II was split into two other sedans so that they could sell different versions of the Mark II at the multiple dealerships Toyota had established in the 1970s. Some models had six-cylinder engines, optionally with electronic fuel injection, borrowed from the larger Crown. For the Japanese market, all Japanese models engines were upgraded with Toyota's TTC-C technology to comply with the Japanese Government's Clean Air Act of 1975. In late October 1977 the 3T-U engine was upgraded to pass the 1978 emissions standards with the aid of a lean-burn design. Four-cylinder engines were mostly reserved for cars intended for commercial usage. The X30-series chassis numbers were the original codes for the third-generation Mark II, with X40 numbers being gradually introduced about halfway through the life of the model for cars that could pass the new, stricter 1978 emissions rules. In October 1979 a diesel-engined Mark II went on sale, a first for the badge as an alternative to the diesel-powered Isuzu Florian. In 1998, Toyota released a car called Progrès. The Progrès front end looks somewhat like an updated version of the X30/X40 series sedan. For instance, both of them feature a combination of round and squared lighting. The grille and bonnet also has similar shapes, size, and lines. Chaser The