Mercedes-Benz: A Brief Test of Three Eco-Friendly Vehicles (1)

Mercedes-Benz Blue Efficiency Models

Brief Test of Three Mercedes-Benz Eco-Friendly Cars (1)

Mercedes-BenzUnder the banner of "Blue Efficiency," Mercedes-Benz is steadily introducing a range of environmentally friendly vehicles to the Japanese market, including clean diesels, hybrids, and small, lightweight engines. Notably, the E250CGI Blue Efficiency Avantgarde has been certified as the first imported car eligible for the eco-car tax reduction.

By Fumio OgawaPhotos by Junki Kono

Environmental Technology Towards Zero CO2

Blue Efficiency is the collective term for the various technologies developed by Mercedes-Benz, which advocates "environmental technology towards zero CO2." The ultimate goal is zero-emission vehicles like electric cars and fuel cell cars, but in the process of reaching that point, they are also striving to reduce CO2 through diverse methods. Specifically, this includes "clean diesel" engines that dramatically reduce the amount of nitrogen oxides in exhaust gas, hybrids that combine electric motors with highly efficient engines, and "CGI (Charged Gasoline Injection)" engines that achieve both fuel efficiency and power through supercharging small-displacement engines.

Currently, the models equipped with "Blue Efficiency" technology introduced in Japan are organized as follows.

• S-Class HYBRID Long (Hybrid)
• E250CGI Blue Efficiency / Avantgarde (CGI Engine)
• E320CDI Avantgarde (Clean Diesel CDI Engine)
• C250 Blue Efficiency Avantgarde (CGI Engine)
• Same, Station Wagon Avantgarde (CGI Engine)

The C250 Blue Efficiency Avantgarde models were launched in Japan on August 25, 2009, the S-Class HYBRID Long on September 3, and the E320CDI Avantgarde on October 6. We had the opportunity to test drive the models in this lineup, excluding the diesel variants.

Mercedes-Benz S-Class HYBRID Long

— A Limousine Building Its Own Unique Value

The S-Class HYBRID Long is enjoying strong sales, with the Japanese subsidiary itself noting it accounts for 40% of all S-Class sales. Its most significant feature is the hybrid system, which combines a 3.5-liter V6 gasoline engine with an electric motor. As an eco-car tax reduction eligible vehicle, it is exempt from 100% of automobile acquisition tax and weight tax.

While the standard S-Class has a body length of 5,100mm on a 3,035mm wheelbase, the "Long" version is larger, measuring 5,230mm with a 3,165mm wheelbase. We heard that Mercedes-Benz Japan chose to pair the hybrid system with the long-wheelbase version partly because they anticipated significant corporate demand. However, it turned out that many individual customers were also opting for the hybrid.

The S-Class HYBRID Long's hybrid system is characterized as a mild hybrid. It features a thin electric motor placed between the engine and transmission, providing functions such as power boost during acceleration, regenerative braking during deceleration, and an ECO start/stop system that automatically shuts off the engine when stopped at traffic lights. Unlike the Prius, it is not a full hybrid that actively utilizes the electric motor.

What Characterizes the Mercedes Approach to Hybrids

Another notable aspect is its early adoption of a compact, lightweight, and highly efficient lithium-ion battery, a first for a mass-produced hybrid vehicle. Because it's a mild hybrid that doesn't require a large battery capacity, the battery is housed in the engine compartment, thus not compromising interior or trunk space.

Furthermore, efforts have been made to enhance the efficiency of the gasoline engine. The 3.5-liter V6 in the S-Class HYBRID Long employs the Atkinson cycle, which improves thermal efficiency by slightly extending the intake valve opening duration during the four-stroke cycle. This results in better fuel economy and controlled exhaust gas generation, a type of system also used in the Prius and Lexus RX. While this enhances environmental compatibility, a drawback is reduced torque in the low-RPM range, which is compensated for by the electric motor's torque. This approach is similar to that of its Japanese counterparts.

Driving the S-Class HYBRID Long, its smooth operation was particularly impressive. Despite its over two-ton weight, the 279-horsepower engine occasionally felt less responsive in acceleration than the numbers might suggest. However, when pressing the accelerator, the electric motor engages. Observing the hybrid system's operation monitor, you can feel the power flow from the motor to the rear wheels, simultaneously experiencing a "boost" function. The car is suddenly propelled forward with a distinct push. This can be considered characteristic of the Mercedes hybrid system.

Its Value as a Flagship is Maintained

The introduction of the S-Class HYBRID Long coincided with a minor change to the entire S-Class lineup, which also included the "Direct Steering" system, where the steering gear ratio changes according to the steering angle. This system is described as enhancing straight-line stability while providing agile handling and ease of maneuverability at low speeds. Indeed, the S-Class HYBRID Long's handling is exceptional; it navigates corners with surprising ease for a vehicle over 5.2 meters long.

Moreover, its chassis performance, body rigidity, and the solid feel of its ride quality all uphold the value expected of the S-Class, Mercedes-Benz's pinnacle model. This was reaffirmed when comparing it with the C-Class and E-Class. Although the S-Class is the oldest in terms of design year, its value as a flagship remains intact.

During a previous test drive of the S-Class HYBRID Long, fuel economy was close to 10 kilometers per liter. Considering its weight, this is remarkably good fuel efficiency. A limousine with high environmental compatibility can also be seen as possessing a unique value proposition.