First drive review: 2021 Porsche Panamera Turbo S and Panamera 4S E-Hybrid prototypes increase power and efficiency

By Ronan Glon for Motor Authority So many loud, high-horsepower machines parade in front of the security guards at Porsche‚Äôs headquarters in Zuffenhausen, Germany, that even a 911 Speedster begins to look a little dull. Arriving to drive 2021 Porsche…