BMW Turbodiesel Mini Cooper D With 60 MPG

Great performing, fun-to-drive cars are the name of the game for BMW and its Mini subsidiary. Now, these characteristics don’t have to be sacrificed in the name of fuel economy. That’s because BMW is turning off power-robbing engine accessories, and even the engine, when they’re not needed. 

BMW’s Brake Energy Regeneration uses an Intelligent Alternator Control (IAC) to disengage the alternator under predetermined parameters. Normally, the alternator is continuously driven via a belt off the crankshaft and draws power from the engine at all times, which means this power is often wasted. With this new system, the alternator operates primarily when the engine is in overrun, such as when descending a hill or braking. When disengaged, on-board electric power demands are provided entirely by the battery. The alternator is also reengaged when the battery requires charging.

IAC uses AGM (absorbent glass mat) batteries that can handle greater loads as well as more frequent charge and recharge cycles compared to conventional lead acid batteries. An AGM battery holds the acid content in micro-glass-fiber mats between the individual layers of lead.

BMW says that on-demand-only generation of electrical energy helps reduce fuel consumption by about 4 percent. Besides better fuel economy, more power is also available for enhanced performance – the reason many people buy BMWs and Minis in the first place.

The Auto Start-Stop Function, available with manual transmissions, automatically turns the engine off when stopped and places the transmission in neutral. The driver engages the clutch to restart. Automatic Start-Stop is turned off with the touch of a button. For regenerative braking, a power converter is installed within the brake system to convert braking energy into electrical power.

Other fuel saving techniques include lower rolling resistance tires and electric power steering. The latter offers energy savings of 90 percent compared to hydraulic steering and works only when required, such as when turning. Six-cylinder 5-Series models also use an on-demand electrical coolant pump that consumes significantly less power than a conventional one and helps and the engine reach normal operating temperature sooner. Additional savings are achieved by disconnecting the air conditioning compressor when air conditioning is not needed.

Switch Point Display on manual transmission cars use the engine management system to analyze speed, road situation, and accelerator pedal position to determine optimum gearing. The ideal gear for best fuel economy is displayed. Even flaps behind the grille improve economy, closing up for improved aerodynamic efficiency when the engine requires less airflow and also improving cold starting times.

BMW will use these systems on the new turbodiesel Mini Cooper D to achieve 60 mpg. This technology is already used in selected BMW 1- and 5-Series models. BMW’s 118d diesel, previously the company’s most efficient model, uses these technologies plus lightweight engineering to achieve 50 mpg.