Mercedes-Benz Bluetec Hybrid: First Look

Motoring Channel Staff - 15/9/2005

At the 2005 Frankfurt motor show, Mercedes-Benz unveiled the 'Direct Hybrid' and the 'Bluetec Hybrid,' two fuel-efficient concept cars.

Using the new S-Class as an example, the company exhibited unique designs for markedly improving fuel consumption and emissions in the near future — while preserving high dynamic ride comfort.

The focus is on combining optimised petrol and diesel engines with a hybrid system and with ultra-modern exhaust gas purification.

"For the drive concepts of the near future the objective is to make petrol cars as efficient as diesels, and diesels as clean as petrol cars," stated Dr. Thomas Weber, Member of the Board of Management of DaimlerChrysler AG, responsible for research and technology and for development at the Mercedes Car Group.

For the petrol engine car, the main emphasis is on reducing fuel consumption even further. With the second-generation spray-guided petrol direct injection system, the engineers at Mercedes-Benz have achieved a crucial innovation that allows considerable fuel savings.

Using the current 3.5-litre V6 as the basis, this technology was implemented under the bonnet of the new S-Class. This vehicle, which incorporates a compact, high-torque electric motor, was presented in Frankfurt as the 'Direct Hybrid'.

Now that the particulate filter has been introduced as standard equipment, the task for the diesel is to adhere to the most stringent exhaust limits worldwide with regard to nitrogen oxide emissions, too - while retaining the celebrated fuel economy.

Nitrogen oxides are currently the only exhaust gas component still emitted in greater quantities by the diesel than by the petrol engine. The goal of achieving the lowest possible emissions has been implemented commendably by the 'Bluetec Hybrid' concept car based on the new 3.0-litre V6 diesel in the new S-Class — and also incorporating a high-torque electric motor.

The crucial element in the success of this system is Bluetec, a new exhaust gas purification technology that reduces the nitrogen oxides by about 80 per cent through selective catalytic reduction (SCR). According to Mercedes, this technology makes the Bluetec Hybrid the cleanest diesel in the world.

Both of the drive systems in the concept cars introduced in Frankfurt are combined with an electric motor integrated in the drive train, thereby becoming what are called “mild hybrids”. This makes it possible to once more significantly reduce the already excellent fuel consumption of the optimised combustion engine, especially in urban stop-and-go traffic.

The combustion engine switches off whenever it is not needed. At other times, the combination of combustion engine and high-torque electric motor act in concert to ensure a powerful and silky-smooth start when pulling away.

Moreover, the electric motor reclaims energy during coasting and braking like most other hybrids. These combined features allow a 20 per cent reduction in fuel consumption in the 'Bluetec Hybrid' relative to the comparable predecessor model, and as much as a 25 per cent reduction in the 'Direct Hybrid'.

The two drive systems not only provide a dynamic driving performance, but also are extremely fuel-efficient and comply with the most stringent emissions standards worldwide. The drive system of the vision S320 'Bluetec Hybrid' have a combined output of 179kW (243hp) and 575Nm of combined torque. The car can accelerate from zero to 100km/h in 7.2 seconds and its top speed is electronically limited to 250 km/h. The vehicle is extremely fuel efficient, consuming only 7.7 litres of fuel per 100 km in the NEDC.

The corresponding values for the S 350 'Direct Hybrid' are 221kW (300hp), 395Nm of torque, 7.5 seconds to accelerate to 100km/h, 250 km/h top speed and 8.3 litres/100 km.

In the coming years, the hybrid - either in its mild or full hybrid configuration - can supplement the combustion engine in certain regions and traffic situations where it represents a reasonable and economical option for increasing dynamics, comfort and fuel efficiency.

Trend-setting examples of such hybrids are the 'Direct Hybrid' and 'Bluetec Hybrid' concept cars introduced to the public for the first time at the '05 Frankfurt Motor Show.