Auto 2000 was an experimental research vehicle developed by Mercedes-Benz and shown to the public at the Frankfurt International Motor Show in the autumn of 1981, alongside the launch of the SEC luxury coupé of the 126 series. It was created as part of a project initiated in 1978 by the German Federal Ministry for Research and Technology (BMFT), aimed at securing a longer-term technological lead for German industry. Three other state-supported research vehicles were shown at the same motor show: one from Audi, the Volkswagen Auto 2000, and the Uni-Car built by a university working group. The Mercedes-Benz entry fell into the largest of the specified vehicle categories in that programme.
The requirements set out for the project called for fuel consumption not exceeding eleven liters per 100 km for a vehicle with a curb weight of up to 2150 kilograms, and 9.5 liters per 100 km for vehicles weighing between 1250 and 1700 kilograms, while accommodating four occupants and offering a payload of more than 400 kilograms. Mercedes-Benz met these targets. The car used the underbody and running gear of the S-Class saloon but featured a slanted SL-style radiator grille, a lowered roofline, and a fastback rear with a Kamm-tail formed from a synthetic-glass rear canopy, giving it a notably modern appearance despite an unchanged body shell below the beltline. Aerodynamic aids included underbody paneling, a rearward-rising spare wheel well, spoilers ahead of the rear wheels, and flush-mounted side glass, targeting a drag coefficient below 0.3; wind-tunnel models achieved an even more refined fastback shape with a long third side window rather than the glass tailgate canopy. A drag coefficient of 0.28 was ultimately achieved.
Three drive concepts were developed for the project. One was a developmental gas turbine, built on a two-shaft principle with a gas generator, compressor wheel and compressor turbine, geared to drive vehicle and turbine ancillaries; its turbine wheels were made of hot-pressed silicon nitride, with other hot-gas-exposed parts made partly from ceramics and partly from heat-resistant metal alloys. Ceramic integral turbine wheels were tested at speeds up to 60,000/min for 140 hours. The complete turbine unit was expected to deliver 94 kW (128 PS) at a combustion-chamber outlet temperature of 1523 K. A variable-pitch guide vane ahead of the working turbine could be used to help brake the vehicle. Earlier gas-turbine research vehicles had come from Rover, Fiat, Renault and American manufacturers, with Japanese firms also pursuing ceramic-turbine development in the 1980s.
A second concept was a 3.3-liter turbocharged diesel V6, replacing an originally planned 4.4-liter naturally aspirated V8 diesel to cut fuel consumption, weight and packaging space; it produced 110 kW (150 PS) at 4600/min using two exhaust turbochargers mounted at a 60-degree angle, with only one turbocharger operating below 2400/min. The light-alloy block used a 90-degree V angle with dry cast-iron liners, light-alloy OHC heads, ceramic exhaust port liners, and a prechamber combustion process; the engine and its automatic transmission were fully encapsulated to meet BMFT noise requirements. The third concept, a 3.8-liter V8 gasoline engine, introduced automatic cylinder cutoff, shutting down four of its eight combustion chambers under low load. All engines used a four-speed automatic transmission. Diesel consumption figures were calculated for both the V6 and gas turbine across urban cycles and constant 90/120 km/h speeds.
Safety measures included a reinforced left-side front structure to address statistically frequent offset frontal collisions, a load-bearing left-hinged bonnet, improved seat belts with three anchor points and pretensioners, a steering-wheel airbag, swiveling rear head restraints, and a removable child seat. Side-impact protection included interlocking doors and door sills, increased passenger-cell stiffness, hip-impact zones, and impact-resistant acrylic glass side windows bonded to light-alloy frames. Aluminum was used for the doors, and glass-fiber-reinforced polyurethane with energy-absorbing foam for the front fenders, bumpers and a "soft-nose" front end for pedestrian protection. Electronic systems included ABS, an early traction-control (ASR) system, a distance-warning device, multiplex wiring, and a driver information system using liquid-crystal displays with software-based instrumentation, alongside onboard trip, maintenance and route computers, the latter functioning as an electronic route planner for the West German autobahn network, plus a communication system for phone calls, emergency calls and traffic information. Mercedes-Benz described the Auto 2000 not as a direct preview of a future production model but as a demonstration of what was technically achievable at the time and what still required further development.
