Excerpt of
http://www.motortrend.com/features/p...m4_first_ride/
"Speaking of cornering, you'll be ordering that up via electric power steering. But fear not, we're assured, the team has sweated the road-feel details like never before. Exhaustive testing of zillions of combinations of racks, ratios, electric motors and rack "transmissions." The end result is a unique rack using the 5 Series' transmission with a smaller electric motor that's quicker to rev. And to keep the steering feel pure, the EPS motor does one thing and one thing only: Helps you dial in exactly as much steering as you wish. It never assists with quotidian tasks like lane centering or returning the wheel to straight ahead after a turn. Nor will it ever counter-steer for you at the stability-control system's behest. And while the rack ratio is still variable, the wildly variable Active Steering will not be offered. The engineer tasked with tuning the new M3/4 steering set the E92 (fourth-gen) M3's hydraulic-assist rack as his personal benchmark. I look forward with guarded optimism to discovering how close he came."
Excerpt of
http://www.caranddriver.com/reviews/...ntended-page-2
T
he electric power steering that he so effortlessly wields might end up as the M division’s greatest triumph regarding these new models. Engineers and executives know the shift from hydraulic to electric assistance comes with enough stigma to fill an X6, and they claim to have taken great pains to ensure they got it right. The M3 and the M4 use bespoke hardware from supplier ZF that makes their steering systems closer to that of the 5-series than the 3-series, but whether it passes judgment ultimately comes down to the calibration. “
We don’t use EPS [electronic power steering] to cover up deficiencies,” says Albert Biermann, head of development for M GmbH, meaning the power-steering motor won’t compensate for understeer, oversteer, a crown in the road, or a coarse road surface. In fact, the lines of code that BMW deleted might be as important as the code that was included.
Even though virtually all electric steering systems use the motor to help unwind the steering wheel, BMW has omitted this function in the M3 and M4. The steering wheel will return to center by the natural self-centering forces of the suspension geometry, just as God intended.
So BMW has altered the recipe with the new M3 and M4, but we like the big torque, that the cars have lost weight, and that M engineers pledge the steering system will become the industry standard. We can’t render a complete opinion, however, until we wrap our hands around the steering-wheel rim and whack some cones for ourselves.