2004 BMW 545i 6-Speed Road Test

Another green light and a sharp turn to the left greet an overpass that spans the highway out of town, a welcome sight

The 545i handled the tight circular onramp like no other car I have tested on it has ever done before. (Photo: Shawn Pisio, Canadian Auto Press)

after the many stoplights that threatened to thwart my intended purpose. The circular onramp that spirals downward to the right before blending into traffic is one of my favorite high-speed testing facilities, and the 545i eats it up and spits it out like no other car I have tested on it has ever done before - and that number of vehicles my friends is well into the hundreds.

The car has an uncanny balance that belies its rather hefty 1,725 kg (3,803 lbs) curb weight, a miracle of modern engineering really. While BMWs are renowned for their high-speed agility, the modern day 5-Series is in a class of one, annihilating any rival through the curves. This is partially due to the conventional methods of a rigid bodyshell, well-engineered aluminum chassis and suspension, plus large diameter, sticky performance tires, but BMW has taken the new 5 a great leap forward with a full assortment of top-tier technology. The driver aids include the usual BMW fare, including DSC (Dynamic Stability Control) with DTC (Dynamic Traction Control), both among the most revered in their categories, plus runflat tires that come standard with a tire defect indicator. BMW sets the 5 apart with the advent of Active Front Steering, Dynamic Drive and Active Roll Stabilization (ARS). Each is tomorrow's technology in today's 5-Series, and their cooperative ability to iron out wrinkled roadways is well beyond an understanding of high school level physics.

Just the same I'll attempt to explain. Essentially active steering adapts the steering ratio to vehicle speed, but its electric-motor-assisted, planetary-gear-motivated rack-and-pinion system is much more sophisticated than conventional speed sensitive steering counterparts, common to luxury cars of

While BMWs are renowned for their high-speed agility, the modern day 5-Series is in a class of one, annihilating any rival through the curves. (Photo: Shawn Pisio, Canadian Auto Press)

all stripes. Steering response to input is much quicker than any other car, at about 1.7 turns lock to lock, making maneuvering into, around and out of tight spaces such as parking lots incredibly easy. To put this in perspective, most cars need about twice that amount to turn the wheel from full left to full right, or about 3.5 turns lock to lock. The reason for this is so steering input isn't too direct at high speeds. At 1.7 turns a car traveling at highway speeds would simply dart off the road with minimal input, not a good thing. Active Steering, however, electronically and mechanically adjusts the ratio to about 4 turns lock to lock when velocities demand, meaning that it is even more stable at high speed than the previous 545i was, and more so than any competitor as well.