Just as quickly as it began to appear, Stuttgart’s traffic thins, and after gliding along for perhaps 15 or 20 seconds — losing remarkably little velocity — I ease back onto the throttle, at which point the rev counter jumps back to life just as quickly as it had extinguished, and the Cayenne eases back up to 95 mph before I slot in amongst slower traffic in the right lane. Beyond the tachometer’s telltale drop and jump, there is exactly no indication that the engine momentarily packed it up just seconds before. My copilot, Dr. Michael Leiters, project manager for Porsche’s Cayenne Hybrid, allows himself a brief smile.
Unlike any other gas-electric system currently on the market, our Cayenne S Hybrid tester has an additional mechanical clutch that decouples the engine entirely, temporarily removing it from the driveline equation. Doing so means the V6 is not a source of parasitic drag, and the modestly-sized 52-hp electric motor can nudge the Cayenne gently along as it does its inertial thing unencumbered.
Source: Autoblog Green