There are many new Porsches heading our way, but one model of particular interest is the next generation of the 911 Turbo, prototypes of which were spotted testing on both the German Autobahn and the Nürburgring racetrack. The word on the street is that the new 911 Turbo models (including the Coupe and Convertible in both regular and ‘S’ trims) will adopt an advanced tri-turbo system for the existing 3.8-litre flat-six gasoline engine. While the power boost will only be around 20hp in both the 991 Turbo and 991 Turbo S for a total of about 520hp and 550hp respectively, the tri-turbo setup will offer improved lower rev range torque and better fuel economy as well as lower CO2 emissions.