Porsche's coveted 911 lineup is about to receive its mid-cycle refresh. Our spy photographers have captured an assortment of trims out testing in recent months, with the cars often fully exposed. The updates will touch every model, including the GT3 and the Cabriolet, which new videos recently captured testing at the Nurburgring race track.

So far, the test vehicles we have seen appear to retain their current front-end styling. However, they have been hiding tweaks at the rear that appear evolutionary in their design, with only minor changes coming to the car regardless of whether it's the GT3, Turbo, or regular Cabriolet. While neither video provides a peek at the revamped 911's interior, previous spy shots revealed that the minor changes coming to the cabin would include a digital instrument cluster.

Porsche uses its naturally aspirated 4.0-litre flat-six engine in the current GT3. It makes 502 bhp and 346 pound-feet of torque, which customers can pair with either the six-speed manual or the seven-speed PDK dual-clutch gearbox. The engine makes 518 bhp in the new 911 GT3 RS, and Porsche could decide to make the refreshed GT3 a bit more powerful, but this is purely speculation.

Powertrain details will remain a mystery until Porsche makes the info officially known. There could be bigger changes coming to the engine lineup that we don't know about. Porsche CEO Oliver Blume reiterated earlier this year that it would add a sporty hybrid to the lineup. Porsche will allegedly set it up to deliver the best performance possible at the expense of added efficiency. We know it won't be a plug-in hybrid.

There was a report from earlier this month that the automaker could use a hybrid powertrain in a new 911 GT2 RS. Porsche will allegedly pair its twin-turbocharged 3.8-litre flat-six engine with a mild-hybrid setup to create its most powerful variant ever. It'll supposedly make over 700 bhp and an "increase" in torque that could be more than the 800-Newton-metres (590 pound-feet) available in Today's Turbo S.

We also don't have any official debut date for the revamped 911 from Porsche, but we could see the first example, in its coupe and cabriolet flavours, debut before the end of the year. Hotter variants like the GT3 and Turbo will likely debut later as Porsche likes to stagger the launch of new trims.