The adjective applys to the E39, the BMW 5 Series now two generations old, sold here from 1996 to 2003. Like the smaller, less costly 3 Series that made the brand the envy of every other premium automaker, the E39 offered the right balance of suspension compliance, sharp handling, and crisp steering. For its feel, feedback, and precision, the E39's steering became a benchmark for BMW's competitors.
The 2004 E60 5 Series was a disappointment for its new, active steering and BMW's least successful application of Chris Bangle's flame-surfacing design language. The car just seemed bigger, heavier, and more complex.
Opt for two pedals and you get eight forward speeds, with tall seventh and eighth gears for improved highway speed fuel efficiency (sixth is "direct drive"). With four planetary gearsets and five clutch packs, the new transmission is designed so that no more than two of its clutch packs freewheel at a given time.
Servotronic, or active steering, is back on the F10 5 Series, though now it's an electronic power steering assist, a first for a car in this segment, according to BMW.
Read more: http://www.motortrend.com/roadtests/sedans/1010_2011_bmw_550i/index.html#ixzz148w61TZC