Mild Hybrids and a CNG/Gasoline vehicle round out their latest offerings.
Wayne Gerdes - CleanMPG
- Mar. 17, 2008
Stuttgart – Mercedes has overhauled the engineering of the B-Class focusing on environmental compatibility, economic efficiency and comfort. Both the diesel and gasoline four-cylinder engines consume up to 7% less fuel and distinguish themselves with remarkably low exhaust emissions that undercut the current EU limits by as much as 90%.
Mercedes-Benz has developed a new ECO start/stop function for the high-volume B 150 and B 170 models that switches off the engine when stopped at traffic lights producing a fuel savings of up to 9% in practical use. Additional new developments include the bi-fuel gasoline/natural gas engine in the B 170 NGT BlueEFFICIENCY.
: Fuel consumption reduced even further
The B-Class continues to be available with a choice of two diesel engines (109 HP and 140 HP) delivering up to 221 lb-Ft of torque. Each has undergone a series of detailed improvements to reduce fuel consumption even further.
The combined NEDC (New European Driving Cycle) fuel consumption of the B 180 CDI and B 200 CDI has fallen by as much as 7% from 43.5 mpgUS to 45.2 mpgUS and 42 mpgUS to 43.5 mpgUS respectively. The B 180 CDI’s range has increased thanks to the more fuel efficient engine and can achieve over 620 miles on a single tank of fuel.
: Fuel-saving ECO start/stop function soon to be an option
Depending on the model and engine output, the gasoline engines of the B Class return fuel consumption figures of between 34 mpgUS and 29 mpgUS on the NEDC driving cycle today. Starting this fall, the gasoline versions become even more fuel efficient with the arrival of the optional B 150 and B 170 BlueEFFICIENCY variants featuring an ECO start/stop system. This newly developed system automatically switches the engine off when the driver shifts to neutral at low speed whilst depressing the brake pedal. If the criteria for stopping the engine are fulfilled, a special display appears in the instrument cluster to inform the driver.
The moment the clutch is pressed or the brake pedal released, the engine springs back to life almost noiselessly and in a fraction of a second. This ability to restart the engine swiftly yet smoothly gives the ECO start/stop system a key edge over other similar basic systems. To achieve this, Mercedes-Benz fits a starter-generator which is connected to the crankshaft via the belt drive. This allows the engine to start much faster and far more quietly than with the conventional starter. The starter-generator supplies the electrical system just as what used to be a separate alternator did previously.
In operation, substantial fuel savings of up to 9% can be achieved with the ECO start/stop function, particularly when driving in city traffic with frequent stops at traffic signs or lights.
: A clean and economical alternative
Another new addition to the B-Class range bears the initials "NGT" on the right-hand side of its tailgate. This stands for "Natural Gas Technology" and identifies a model which is as economical as it is environmentally friendly courtesy of its bi-fuel drive. The B 170 NGT BlueEFFICIENCY is able to run on either natural gas and premium gasoline.
In addition to the gasoline tank, there are five natural gas reservoirs whose total capacity of 16 Kg’s equates to a range of over 185 miles. With overall NEDC consumption figures of 32.2 mpgUS on premium and .078 Kg of natural gas/mile, the new B 170 NGT BlueEFFICIENCY is able to attain a total range in excess of 620 miles. The driver determines which fuel source the engine is to run on at the touch of a button located on the steering wheel.
The four-cylinder engine has been modified by Mercedes-Benz to include additional gas injectors on the underside of the intake manifold. A close-coupled pressure governor with electromagnetic shut-off valve regulates the supply of natural gas and keeps the pressure within the system constant.
The installation of the rear CNG tank reduces the cargo capacity of the B Class by 4.5 cu. ft. to 14.9 Cu. ft. with more than sufficient space for carrying a family's luggage.
The lower CO2 emissions and cheaper fuel costs make natural gas an attractive alternative to both gasoline and diesel in terms of emissions and costs. On the NEDC cycle, the CO2 emissions are 17% lower than the gasoline powered B 170 at 135 g/km. If the natural gas consumed by the new B 170 NGT BlueEFFICIENCY is converted into the equivalent quantity of gasoline energy, the fuel cost per mile is reduced by almost 50% vs. running on straight gasoline.
B-Class engine, performance and fuel consumption
LCA (life cycle analysis) for NGT
|Engine||B180 CDI||B200 CDI||B150||B170||B170 NGT|
0 – 62 mph||11.3||9.6||13.2||11.3||12.4|
Top Speed (mph)||113||124||108||114||114|
*FE (mpgUS)||45.2||43.5||35.6||34.6||** 50|
* NEDC Combined mpgUS
** Approximate mpg per gallon equivalent.
A NG power B-Class traveling 93,000 miles shows an overall CO2 emissions decrease of 20%, NOx emissions are 11% lower and CO is 54% below the comparable gasoline model over the vehicle's lifecycle using NG. The higher CO2 cost of the manufacturing the B 170 NGT is balanced out after a distance of only 10,750 miles.
MB Start/Stop MGSet layout
Current pricing of the more fuel efficient MB B-Class diesel, gasoline and gasoline/CNG powered vehicles including the optional Start/Stop system has yet to be released.