Remember when enthusiasts all decried the imposition of regulations on emissions, saying that government regulation would make our cars pale shadows of what they had been? And they all believed that, never imagining that we would arrive at the present situation, with luxury limousines like BMW's Active Hybrid 7 - to use the official nomenclature - accelerating to 60 mph in less than five seconds, running to 155 mph (an artificially restrained Gentleman's agreement figure), while being both more economical and cleaner.
The 7 Hybrid is a magnificent engineering achievement. It not only attains the "impossible" standards we now demand, but is also a good bit faster, quieter and easier to live with than the basic internal combustion only model. Technologies developed in concert with Mercedes-Benz allow BMW to add features formerly unavailable, like the transparent stop-and-start system. When you come to a stop, the V-8 shuts off, leaving the cabin absolutely silent, and releasing the brake pedal has the engine running in microseconds, the car already moving under the impulsion of the 51-pound three-phase synchronous 20 hp 120 Volt electric motor interposed between the crankshaft of the twin-turbocharged V-8 and the all-new eight-speed automatic transmission when there is the slightest touch on the throttle.
BMW is not new to turbocharging. There was a 2002 Turbo in the Seventies, one of the first applications in series production, and the 745i was essentially just a a turbocharged 733i E-23 sedan, but earlier models were achieved by adding a turbo to an existing engine. The V-8 in the current 750i and 750iL models is completely new, conceived specifically to be blown, with the turbos nestling in the vee of the block, and intake coming through the underside of the heads. in the Hybrid 7 the engine is stripped of most of its accessories. There is no starter; that function is handled by the integrated traction motor. The air conditioning compressor under the hood is electrically driven by the 120V system - which means that it can be remotely activated to cool the cabin down before anyone gets into the car, a very luxurious touch in hot climates.
The whole mild hybrid system, including the 60 pound Lithium-ion battery pack in the trunk, adds some 220 pounds to the already hefty 750i (around two and a quarter tons in the lightest model). In compensation there is a 17% reduction in CO2 and an increase in total power from 407 to 465 bhp. Torque is up 16.7% and the heavier Hybrid gets to 100 kph (62 mph) three-tenths of a second quicker. Any time the brake pedal is activated energy is recovered and fed into the battery, located just behind the rear seats in space that is ordinarily used for a rear A/C unit. The battery is protected by a sturdy shield as a safety measure.