Here is one of the latest spy shots of a virtually undisguised next-generation Porsche 911 having a workout close to Porsche's Stuttgart factory. It's one of the clearest yet and probably the best you can expect before the car's official presentation at the Frankfurt Motor Show next month. The next 911 will be 4.49m long - 56 mm more than the current model with 10mm extra wheelbase. The car will also stand 11 mm shorter. The 3.4L entry-level Boxer engine (down from a 3.6L unit) has an output of 350hp, good for a 0-to-100kph sprint time of 4.8 seconds and a top speed of 289kph. The smaller, more-efficient unit will reduce fuel economy by 13 per cent to 8.5L/100km. Moving up, the Carrera S will reward drivers with 395hp, while the 911 Turbo is rumoured to have an output of approximately 542hp.