It's no secret that Porsche will be revealing the all-new 911, codenamed the 992, later this year, which was recently previewed by the German automaker. We've already seen spy shots of prototype mules, and on first glance the 911 spotted by our spies in these latest photos appears to be another regular 992 prototype. However, a closer inspection reveals a few changes, so we could be looking at something different. This prototype has a different exhaust system than the 992 turbo prototypes, and the rear bumper has other air outlets.

But perhaps the most obvious addition is the center lock wheels, which are typically fitted to high performance Porsche 911s. If you haven't guessed already, what we could be looking at here is an early prototype of the next generation Porsche 911 GT3. Reports have suggested that the current 991.2 GT3 will be the last naturally aspirated GT3, which explains why the exhaust on this prototype looks like the one used on the GT2 RS rather than the current GT3. Instead, there's a good chance the next GT3 will drop the naturally aspirated flat-six in favour of a turbocharged unit. Rumors suggest it could pack 550 horsepower, which would be a substantial increase over the current 500-hp model.

It may also be offered exclusively with an eight-speed PDK gearbox in contrast to the regular 2019 Porsche 911, which will have an optional manual gearbox. Purists won't be happy, but a PDK delivers better performance, which is obviously the main focus for the GT3. The new Porsche 911 is expected to debut later this year at the Paris Auto Show in October, so the 992 turbo and GT3 will most likely debut in 2019 or 2020.