The Mercedes-Benz E 200 NGT made its debut on Germany's roads in the spring of last year. In mid-2004, availability of this clean-running variant of the E-Class, which cuts CO2 emissions by over 20 per cent and more than halves running costs, was extended to Austria, Italy, Sweden and Switzerland. A right-hand-drive version is due to become available for the Thailand market this year.
Natural gas presents itself as an economically and ecologically viable alternative to petrol and diesel. As a primary energy source, it can be used in its natural state, avoiding conversion costs. The most suitable form of natural gas for use in cars is compressed natural gas, which is largely the form it takes when extracted.
Engineers at the Mercedes-Benz Technology Center have developed a natural-gas-powered vehicle with bivalent drive system based on the E 200 KOMPRESSOR. The 120-kW/163-hp four-cylinder unit can be supplied either with natural gas or premium-grade unleaded petrol � the driver decides which type of fuel is the most appropriate, using the buttons on the multifunction steering wheel and the central display in the instrument cluster to switch between natural gas and petrol. A special electronic control unit ensures a particularly smooth transfer from one power source to the other and regulates the process for each cylinder individually.
The TWINPULSE supercharged engine has been modified to accommodate the new fuel type, with additional injection nozzles fitted on the underside of the intake manifold. A pressure regulator located close to the engine with sensor and electromagnetic shut-off valve controls the supply of natural gas and maintains the necessary system pressure. The exceptional output and torque characteristics of the leading-edge four-cylinder unit are undisturbed by the switch to natural gas power � the E 200 NGT (Natural Gas Technology) is currently the most powerful saloon to run on natural gas. The most important data and performance values for the Saloon are as follows:
E 200 NGT petrol-driven engine Natural-gas drive system
Displacement 1796 cc 1796 cc
Output 120 kW/163 hp 120 kW/163 hp
0�100 km/h 10,7 s 10,8 s
Maximum speed 227 km/h 227 km/h
Energy consumption 9,0 l/100 km* 6,0 kg/100 km**
*NEDC combined fuel consumption; **Natural gas of quality rating H
Natural-gas drive system produces over 20 percent lower CO2 emissions
Like the petrol-engined variant, the E 200 KOMPRESSOR with bivalent petrol/natural-gas drive system also meets the stringent exhaust gas specifications of the EU-4 standard. Indeed, carbon dioxide emissions during natural gas operation are more than 20 percent lower than when the petrol drive mode is selected.
The innovative new E 200 variant is fitted with a 65-litre petrol tank, as well as gas tanks with a total capacity of 18 kilograms which are stored safely in the spare-wheel well in the boot area and behind the rear wall of the rear passenger compartment. With this supply of energy on board, the petrol/natural-gas vehicle has a total range of some 1000 kilometres when calculated according to NEDC consumption figures � almost 300 kilometres under natural gas power and another 700 kilometres with conventional petrol fuel (provisional data). The saloon may also be equipped with an 80-litre petrol tank, extending the maximum range to nearly 1200 kilometres. A special gauge in the central display of the instrument cluster informs the driver of how much gas remains in the tanks. If the gas supply has been used up, the system switches automatically to petrol drive.
The gas tanks reduce the load capacity of the boot from 540 to 400 litres but still offers enough space for two large �jumbo� suitcases plus two other smaller travel bags. The new E-Class Saloon variant comes with a five-speed automatic transmission and has a payload capacity of over 500 kilograms.
From the outside, the E 200 KOMPRESSOR with bivalent drive system is virtually identical to the standard E-Class Saloon. Only the tank flap has somewhat larger dimensions of about 60 millimetres, with the conventional filler pipe for petrol accompanied by a special natural gas filling connection, which ensures safe and easy refuelling.
Comprehensive crash testing to ensure trademark Mercedes safety
The two fuel sources are stored in a petrol tank with a capacity of 65 litres and four gas reservoirs with a total storage capacity of 18 kilograms respectively. The reservoirs are located in the spare wheel well. The E-Class with bivalent petrol/natural-gas drive system has already completed a rigorous programme of testing at the Mercedes-Benz Technology Center, emerging from some extremely exacting durability examinations and a range of different crash tests with flying colours. The leak tightness of the gas reservoirs was subject to particularly rigorous scrutiny, after all the natural gas that is pumped into the reservoirs during refuelling is compressed to a pressure of 200 bar.
Serious savings at the pumps
In addition to considerably reduced CO2 emissions, the natural-gas drive system also offers sound economic benefits. At the present time, a kilogram of natural gas costs at 8.50 Baht in Thailand, while premium unleaded petrol will be 22.14 Baht per litre (retail price quoted on 3 June 2005). Petrol consumption by average, thus will cost approximately 9.4 - 9.6 Baht or 208 - 213 Baht per 100 kilometres in other words. Comparison to running vehicle on natural gas requires at 6.1 kilogram or 52 Baht per 100 kilometres. This makes natural gas over 50 % more cost-effective than premium unleaded petrol.
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