push buttons in the middle for directing the air flow and switching the system on and off and a vertical set of buttons on the right for controlling the fan speed and switching automatic control on and off. All models except the 280, 280 E, and coupé feature larger round headlamps with smaller round fog lamps with large glass plate covering the entire headlamp housing and acting as a diffusing lens. This setup is the same for North American models with the sealed beam units and glass plate partially covering the headlamp housing. The 280, 280 E, and coupé models use large rectangular headlamps with round fog lamps. The headlamp washers and wipers set are optional. Nomenclatures Per Mercedes-Benz tradition (prior to the 1994 change), model designation corresponded to the engine displacement, chassis type (coupé or estate/station wagon), fuel type (for diesel engines only), and availability of fuel injection system (for petrol engines only): C for Coupé T for Tourismus und Transport (estate/station wagon) No designation was given for the long-wheelbase: it was simply called "Lang" (long) in the brochures and order forms. D for Diesel E for Einspritzung (fuel injection) When the diesel engine is turbocharged, TURBODIESEL is affixed to the right side of the boot lid. As for the chassis codes, W123 is the saloon/sedan, S123 the estate/station wagon, C123 the coupé, V123 the long-wheelbase saloon/sedan a.k.a. Lang, and F123 refers to the bare long-wheelbase chassis as used for ambulances and other conversions. Model variations Saloon (W123) The four-door version went on sale on 29 January 1975. Coupé (C123) In the spring of 1977, a coupé version was introduced on a shortened wheelbase ( versus for the saloon). The C123 was available as 230 C (later 230 CE) and as 280 C and 280 CE in most markets. Unlike the W123 saloon, the rectangular headlamps were fitted to the C123 regardless of engine type. Limousine (V123) From August 1976, a long-wheelbase version () with seating for seven to eight was produced. The limousine was built on a stretched W123 saloon/sedan chassis with lower side panels from the coupé behind the rear passenger doors. The elongated roof has the same C-pillar form as on the saloon/sedan. The rear passenger doors were custom-designed in rectangular shape and of the same length as the ones on the saloon/sedan. The engine options were 250, 240 D, and 300 D. A few 280