Porsche's top-secret mid-engine replacement for its venerable rear-engine Porsche 911 RSR GT racer continues to test a Sebring's 3.7-mile road course in Florida. The semi-private facility has given the German brand's fans a look at the new-for-2017 machine in action around the former airfield, and among the most notable departures from its predecessor, the RSR's rear window has been transformed into a source of air entry and extraction.
The forward movement of the Porsche's flat-6 engine has also given the RSR's engineers room to fit individual exhaust pipes. The pair of straight pipes replace the combined unit that joined behind the motor and exited in the middle of the car from 2014-2016 .
In concert with the new exhaust options, shifting to a mid-engine layout created new opportunities to exploit a more aggressive diffuser. Saddled with the rear-engine installation, the former diffuser was shallow due to the real estate occupied by the boxer's footprint. With the motor now positioned closer to the cockpit, the open space where the motor once sat has been used to produce a steeper diffuser solution. The new diffuser will give the 2017 RSR more underbody downforce which should allow the cars to be run with lower rear wing angles than were possible with the previous car.
Porsche has kept the car's details quiet, and declined requests to discuss even the most basic aspects of transitioning from decades of rear-engine 911 designs to the new mid-engine-style installation. We've even speculated that this car might not be called a 911. For now, the testing video below, captured by a Sebring local and , provides the best glimpse of what's to come next season.