The Porsche Cayenne wears many hats. It masquerades as both the automaker’s entry-level vehicle and as its flagship turbocharged SUV. Broad-shouldered in stature, one variant can blast to 60 mph in less than five seconds and top 170 mph, while another may be propelled quietly under the emissions-free... 

We’re the lone vehicle in the far left lane of the Autobahn outside of Köln, Germany. The traffic has lightened, so we mash the accelerator to the floor. While we pull strongly up to about 200 km/h (about 125 mph), the speedometer counts much more slowly as it spins around the right side of the...