BMW 118d an Ultimate Hybrid Fighter
By Bill Siuru
The clean diesel BMW 118d just may be the ultimate hybrid fighter. This three- and five-door BMW turns in an impressive 52 mpg on a combined cycle with CO2 emissions of just 119 g/km, clearly running in the rarefied territory where only the most efficient hybrids tread. That is indeed good news. The bad news is that even though BMW now offers the 1-Series coupe and convertible in the U.S., the diesel variants of the 1-Series – as well as three- and five-door sedans – are not planned for this market.
A product of BMW’s EfficientDynamics program, the 118d features technologies like brake energy regeneration, automatic start-stop, and electric power steering. An optimum gearshift change indicator encourages economical driving by suggesting when to upshift for best fuel economy. Low rolling resistant, run-flat tires are part of the package.
Brake energy regeneration uses an intelligent alternator control (IAC) and an absorbent glass mat battery to recoup braking energy. IAC reduces drag on the engine by only engaging the alternator when required to charge the battery, thus contributing to fuel efficiency. Also, previously wasted energy generated when braking or descending a hill is used by the IAC for charging the battery. Brake energy regeneration contributes a three percent improvement to overall fuel economy.
The automatic start-stop system automatically switches the engine off when the vehicle is stopped and in neutral. To restart, a driver need only engage the clutch again before pulling away. It can be switched off if not wanted. Electric power steering also works only when required such as when turning a corner, resulting in a 90 percent energy saving compared to a conventional hydraulic steering system.
Other fuel saving features are included in the design. Among these are air conditioning that disconnects from the drivetrain when not in use and flaps behind the grille that close for improved aerodynamic efficiency when the engine requires less airflow. The latter also shortens cold start times for improved emissions control.
The 118d is powered by a turbocharged 1995cc, 16 valve four-cylinder aluminum engine. Its second generation common-rail injection produces 143 horsepower at 4000 rpm and 258 lbs-ft of torque at 2000 rpm. The standard transmission is a six-speed manual. Like all BMWs, it has rear-wheel drive.
Being a BMW, performance is also impressive: top speed is 130 mph and 0-62 mph (0-100 km/h) is achieved in 8.9 seconds. A more potent 120d engine with the same displacement but offering 177 horsepower is available on a 1-Series coupe, five-door, and convertible. This engine achieves a higher 142 mph top speed and 7.5 second 0-62 mph time while netting a somewhat lesser 48 mpg fuel economy figure.
Want to know more about advanced technology BMW vehicles? Be sure to check out these articles on GreenCar.com:
BMW Vision EfficientDynamics Hybrid Concept
BMW’s Advanced 335d and X5 Clean Diesels Coming to American Roads
BMW Dual-Fuel Hydrogen 7
Green Cars on Yahoo! Autos
Biodiesel technology on Yahoo! Autos
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