Development of the next-gen Porsche 911 Turbo continues, and a new gallery of photos catches two of them while filling up with petrol during a stop while testing in Nevada. We have to thank a reader of's Italian edition who snapped these pictures and shared them with us.

Porsche 911 Turbo, the spy photos
Porsche 911 Turbo S, the spy photos

The two test prototypes are identical from the front, but you can notice the differences at the back. One of them wears black, five-spoke wheels and has a pair of oval-shaped exhaust outlets. This is likely the standard 911 Turbo. The other has fork-spoked wheels and four trapezoidal pipes at the back. This one is probably the hotter Turbo S.

Compared to the 911 Carrera, the Turbo models have wider fender wings and a revised rear deck. Rather than incorporating a spoiler into the curve at the tail, there's an active wing at the back.

The new models reportedly use an evolution of the previous gen's 3.8-litre twin-turbo flat-six engine. The standard Turbo allegedly has 600 bhp, and the Turbo S would take the output to around 640 bhp. Expect the drivetrain to continue to be all-wheel drive and running through an eight-speed dual-clutch gearbox.

After missing the Frankfurt Motor Show, the 911 Turbo could make a debut at the Los Angeles Auto Show in November. If there's not a public premiere in California, the next possible arrival would be at the Geneva Motor Show in March 2020. After the coupe, spy shots already tell us that the 911 Turbo Cabriolet should come soon afterwards.

Gallery: Porsche 911 Turbo spy shots