Driving BMW's "Efficient Dynamics"

BALI, INDONESIA – High style and scintillating performance are what BMW is famous for. However, in the face of growing concerns for the environment and sustainable mobility, the German powerhouse would like customers to know that their cars are not only highly satisfying driving machines but extremely energy-efficient as well. And while the goal of a full electric vehicle is still yet to be realized, that doesn’t mean the conventionally powered vehicles they have right now are slouches in the energy-optimization department. Far from it, in fact, as a day test driving their cars in Bali would show. Brake energy regeneration, lightweight aluminum chassis, high pressure injectors... BMW employed nearly every trick in the book to get the most out of their Internal Combustion Engined (ICE) vehicles.

With a fleet of X1s, X5s, X6s, 5- and 3-Series sedans to choose from, BMW proved that even a regular production car can provide excellent performance and fuel efficiency. Yes, Virginia, you really can have your cake and eat it, too. So long as you’ve got the cash to buy a BMW, of course.

Brake Energy Regeneration – The market first became largely aware of this technology when it was applied to hybrids like the Toyota Prius and Honda Insight. But who says only hybrids and Electric Vehicles can use it? With BMW, the technology as employed in the 5-Series, X5 and up charges the battery as soon as the driver lifts off the throttle or steps on the brakes. This reduces fuel consumption by lessening the load on the engine to charge the battery, as well as ensuring full engine power is freed up for acceleration.

Auto Start/Stop Function –­ Prolonged stop-and-go driving in the city is notorious for consuming fuel. With this function, the engine is automatically shut down after a predetermined period of time in order to conserve fuel. A seamless restart is also initiated the moment the driver steps on the accelerator.

Aluminum construction  – With the use of aluminum for the hood, roof, and even the rear axle drive of the 5-Series, overall weight is reduced, contributing to fuel efficiency as well as lowering the car’s center of gravity for improved handling.

Low drag, low friction, low rolling resistance – Carmakers take pains to create attractive and practical designs that also slip through the air as efficiently as possible, but BMW goes one step further with electronically controlled vents in the radiator that automatically open or close to either optimize cooling or reduce drag. The use of low rolling resistance tires also means it takes less energy to get their cars moving along.

Optimized auxiliary units – In concert with the battery that’s partly charged by Brake Energy Regeneration, auxiliary units such as the power steering pump, water pump, pressure controlled fuel pump, and an automatically decoupling air conditioning compressor are now driven electrically instead of relying on engine power.

Engine optimization – Of course, BMW is a driver’s car brand. As such, the company has gone to great lengths to extract the last bit of power out of its combustion engines. Whether gasoline or diesel, high precision injection technology enables extremely efficient fuel combustion. The Piezo injectors are positioned centrally between the valves, allowing the proportion of fuel in the combustion mixture to be reduced. In normal operation the fuel-to-air ratio is 1:14.7, while in lean-burn mode it can go to as low as 1:34 depending on the engine load. Of course, aside from reduced fuel consumption, this also reduces emissions.

Taking all these technologies combined, BMW is proud of the fact that even though its cars have gained more power over the years, they have also become more fuel efficient. As an example, the current BMW 320d is rated at a healthy 184 hp, yet now consumes only 5.3 liters per 100 kilometers. For its entire fleet, C02 emissions have gone down by nearly 29% from 1995 to 2009 in Europe.

What’s next? – With the vision of BMW “Efficient Dynamics”, optimization of the existing gasoline and diesel lineup is just the first step. The company now employs “mild hybrid” technology for high-end flagships like nonreactive 7 and X6. As it moves toward full electric and hydrogen vehicles, the company is now looking at “Predictive Energy Management”; combining all the sensor input to manage the engine and auxiliary units for the lowest possible energy and fuel consumption. For example, in cooler climes it could raise the engine temperature and thus lower engine friction. On the other hand, in hotter climates it could lower the engine temperature and thus free up more torque.

It is also looking at “thermal recuperation”, since fully 2/3rds of the energy produced is wasted. The concept is borrowed from deep space technology, where thermoelectricity has been applied to deep space exploration for the past several decades. Applied to automobiles, waste heat from the exhaust could be converted to electrical energy via a special thermoelectric material.

So, how does all this current technology work? Very well, in fact. With the keys to an X1 and a 5-Series for the day, we explored the winding roads of Bali where moderate traffic and tight turns necessitate a lot of accelerating and braking. None of the newfangled fuel/energy-saving technology detracted from the simple pleasure of navigating as fine a machine as the 523i; our only indication that it was working being a “Brake Energy Regeneration” light discreetly activating on the instrument panel whenever I let off the throttle or stepped on the brake. At the end of the drive, we registered an impressive 9+ kilometers per liter even without resorting to “hypermile” techniques like freewheeling or turning off the air conditioner (it was too humid anyway). Optimized engine technology, regenerative brakes, low rolling resistance... none of this would be as impressive if they didn’t work as seamlessly and invisibly as they do in BMW’s fleet.

Are they Efficient? Yes. Dynamic? Definitely.