Natural gas is becoming an increasingly popular alternative to gasoline and diesel in Europe. It’s less expensive than these conventional motor fuels and has lower carbon dioxide emissions. Also helping is the growing availability of natural gas, with nearly 800 compressed natural gas (CNG) refueling stations in Germany, 600 in Italy, 100 in Switzerland, and 90 in Austria.
Mercedes-Benz has joined in to lend its emphasis to the viability of natural gas vehicles with a bi-fuel engine option for the redesigned 2009 B-Class. The B 170 NGT BlueEFFICIENCY joins B-Class models powered by 1.5- and 1.7-liter gasoline engines (B 150 and B 170), 1.8- and 2.0-liter diesel engines (B 180 CDI and B 200 CDI), and a turbocharged 2-liter gasoline engine (B 200 TURBO). All are four cylinder powerplants.
Identified by "NGT" – for Natural Gas Technology – on the tailgate, the B 170 NGT BlueEFFICIENCY Sport Tourer delivers an identical maximum output of 116 horsepower on either gasoline or natural gas. A driver selects the fuel using a button on the steering wheel. An electronic control unit switches fuel source instantaneously and seamlessly, even while driving.
Mercedes-Benz added four additional gas injectors on the underside of the intake manifold to handle natural gas. A close-coupled pressure governor with an electromagnetic shut-off valve regulates the supply of natural gas and maintains a constant gas pressure in the system.
In addition to the gasoline tank, there are five compressed natural gas tanks with a total capacity of 35.2 pounds, providing a range of over 180 miles. The B 170 NGT has a total range of over 620 miles on both fuels. The tanks are located in the rear and beneath the front passenger footwell. Trunk capacity is about 25 percent less that conventional models but still sufficient for carrying a family's luggage.
The B-170 NGT achieves 32 mpg on premium gasoline as measured on the combined European driving cycle. According to Mercedes, the cost of running on natural gas is around 50 percent less than on gasoline.
Carbon dioxide emissions are some 20 percent lower than in the gasoline-powered B 170 at 135 gm/km, with NOx emissions 11 percent less. When calculated on a total lifecycle basis, carbon monoxide emissions are reduced by over 50 percent. While more CO2 is produced in manufacturing the more complex B 170 NGT, this is balanced out by the savings offered when running on natural gas after 10,730 miles. Germany’s TÜV Technical Inspection Authority has awarded a "Design For Environment" to the B 170 NGT, the first natural gas-powered car to receive the award.
Also new for the B-Class is an ECO start/stop function that’s optional on B 150 and B 170 BlueEFFICIENCY models. ECO automatically turns the engine off when the driver shifts to neutral at low speed while depressing the brake pedal. If the predetermined criteria for engine shut-down are met, a display on the instrument panel informs the driver. When the clutch is pressed or the brake pedal released, the engine starts almost noiselessly and in a fraction of a second. It doesn’t have regenerative braking. Mercedes-Benz says the belt driven starter-generator produces a fuel saving of up to nine percent.
The B-Class is available in Canada although only the B 200 and B 200 TURBO are now sold there. There are currently no plans to bring the B-Class to the U.S., although that’s a scenario we hope will change as the market for small cars – and of course natural gas-powered cars – increases in response to high gasoline prices and concerns about CO2 emissions.
