Both the prototypes spotted by our photographers have filler caps on both rear flanks, indicating that the cars seen here are plug-in hybrids. It's not known at this stage whether the plug-in hybrid drivetrain in the new car will differ significantly from the current model's.
In the current-generation Panamera, the S E-Hybrid has a total output of 306kW of power and 590Nm of torque. To achieve these figures, the S E-Hybrid utilises a 245kW/440Nm 3.0-litre supercharged V6 petrol engine, a 70kW/310Nm electric motor and an eight-speed auto.
Overall it drinks 3.1L/100km and is capable of up to 36km of pure electric motoring. In EV mode, the current-gen Panamera is able to hit a top speed of 135km/h. With both motors running, the current car reel off the 0-100km/h standard in 5.5 seconds.
As in the current range, the Panamera plug-in hybrid will be sold alongside other drivetrain options, including V6 and V8 petrol motors, and V6 turbo-diesels.
The new Panamera will be the first model to utilise the Volkswagen Group's new MSB component matrix for rear- and all-wheel drive vehicles. Thanks to the use of high-strength steel and lightweight materials, such as aluminium and magnesium, the next-gen Panamera should be lighter, faster and more efficient.
Last year, Michael Mauer, Porsche's design chief, told Car Advice that new Panamera "will look better" and will feature a faster roofline, with some headroom sacrificed on the altar of improved looks.
The new car, as borne out by these and earlier spy pictures, does indeed feature a more svelte and less bulbous look, especially at the rear.
It's expected that the new Panamera will debut towards the end of 2016 and go on sale in Australia from 2017.