The 380 SEC and 500 SEC S-Class coupes (126-series) make their debuts at the Frankfurt International Motor Show. Another first on display is the Mercedes-Benz Energy Concept, which permits significant reductions in the fuel consumption of the six and eight-cylinder passenger cars in particular. Another new product is a 200 saloon (123-series) equipped to operate on petrol or liquefied petroleum gas and scheduled to go on sale starting in autumn 1982. Mercedes-Benz presents Auto 2000 at the motor show as a test vehicle for developing innovations in passenger car design. It tests three different drive units: a V6 diesel engine with compound turbocharging, a V8 petrol engine with cylinder cut-out system, and a gas turbine. In the commercial vehicle sector, the van series introduced in 1967 (internally designated T 2) makes its debut with improved design and equipment along with the 4.6-tonne variants of the light van series presented in 1977 (internally designated TN or T 1). Also new are two large-displacement, very economical naturally aspirated engines, which find use in medium and heavy-duty trucks: the OM 421 V6 and the OM 423 V10.