With its F 700 research car, Mercedes-Benz redefines the idea of effortless, superior refinement: this concept for a future luxurious touring sedan shows how outstanding riding quality can be combined with high levels of environmental friendliness, and good performance with exceptionally low fuel consumption. Thus, the 5.17 m long F 700 with its innovative and very spacious interior design enables an entirely new and exceedingly comfortable mode of travel. The F 700 is the world’s first car that can anticipatively recognise the condition of the road and level out the uneven spots with its active PRE-SCAN suspension, further improving suspension comfort substantially. The forward-pointing DIESOTTO drive system introduced in the F 700, a four-cylinder with a displacement of only 1.8 litres, combines the strong points of the low-emission gasoline engine with the consumption benefits of the diesel drive. Its CO₂ emissions of a mere 127 g/km correspond to consumption of 53.3 mpg, extremely low for a vehicle of this class.

This is made possible by a forward-looking drive concept, the heart of which is the “DIESOTTO” technology – an advancement of the internal combustion engine thought up by Mercedes-Benz. With its novel controlled auto ignition (CAI), direct fuel injection and turbocharging, it combines the high power of the spark-ignition engine with the exemplary torque and great fuel economy of a diesel. The drive system in the F 700, as four-cylinder featuring two-stage charging, attains the performance level of a current S-Class car with a 3.5-litre naturally aspirated V6 gasoline engine or the 3.0-litre V6 turbodiesel.

“Our goal is to make the petrol-powered car just as economical in consumption as the diesel. The new DIESOTTO concept is a major step in that direction, combining the best properties of the spark-ignition engine and the diesel engine,” says Dr Thomas Weber, Board member of DaimlerChrysler AG responsible for Group Research & Mercedes Car Group Development.

The exterior design of the F 700 shows that with this concept an extraordinary amount of space has been created for the passengers. The very silhouette, characterized by the long wheelbase, is a clear indication of this. The design harmoniously joins together inspirations provided by nature with technical innovation. All the futuristic styling devices notwithstanding, the F 700 is perfectly compliant with the brand identity of Mercedes-Benz.

The F 700 meets the growing demands on luxury-class automobiles. The focus is on conserving resources and protecting the environment: low consumption, low CO₂ emissions, low pollution levels. For in future there will continue to be considerable demand for the comfortable mobility provided by large saloons.

The first step to less consumption is to downsize the engine. Instead of a big-volume, naturally aspirated engine, a compact, turbocharged power plant is used. This leap backwards in cylinder size and displacement reduces internal friction in the engine. The smaller unit increasingly runs in a more efficient combustion range. The drive system in the research car is a four-cylinder with a displacement of a mere 1.8 litres. At first, this is somewhat of a surprise for a vehicle of the luxury class, where up to now at least six cylinders and three litres displacement are the standard.

The sensation of effortlessly superior driving in the luxury class nonetheless is retained. The DIESOTTO drive gets additional power from a two-stage turbocharger system. A larger low-pressure turbocharger and a high-pressure turbocharger of smaller diameter are connected in series and together optimally cover the complete engine speed range. The complex system makes for good responsiveness from low revs, provides high torque and pulling power and delivers high peak output. For driving off, the internal combustion engine additionally gets assistance from the electric motor of the hybrid module.

The maximum output of the internal combustion engine is 238 hp; the electric motor develops another 20 hp; the maximum torque of the system is impressive 400 Nm. This guarantees performance commensurate with the luxury class, as the time of 7.5 seconds for the 0 to 62 mph sprint documents.

The hybrid module with its integral starter-generator helps to even further reduce the excellent fuel consumption mainly in urban stop-and-go operation. The internal combustion engine always is shut off when it is not needed. On moving off, the combination of internal combustion engine and torquey electric motor is a tandem that ensures a powerful but silky smooth start. Besides that, during coasting and braking the electric motor recovers energy which is stored in a special high-voltage battery and used for the next starting operation. This starter-generator is integrated in the housing of the 7G-TRONIC automatic transmission.