The redesigned sedan will likely go on sale at U.S. Porsche dealerships during the first half of 2017.
The 2018 Panamera is new from the tires up and is said to feature a weight-reduced body structure, all-new V8 and V6 engines, a new dashboard featuring modern touchscreen controls and a more luxurious interior.
The 2018 Panamera has been seen testing at the Nürburgring race circuit in Germany carrying relatively little visual disguise, to reveal a car similar in style and silhouette to the existing model.
It retains a liftgate at the rear and, like the current model, appears to be a strict four-passenger car, the individual seats placed on either side of a deep center console to produce an unusually low and racecar-like seating position for all occupants.
The new body shell is constructed from a variety of materials designed to maximize strength and minimize weight.
They include aluminum, magnesium and high-strength steels that are said to save over 100 pounds from the body. The overall weight of the new Panamera is thought to be much the same as today's model, but the car will be safer and carry more equipment.
The car is built around the Volkswagen Group's so-called MSB large-car modular architecture that is shared across several of the Group's luxury brands including Audi and Bentley. The architecture is highly flexible, allowing cars of very different heights and proportions to be produced on the same production machinery.
The new Panamera is said to ride on a slightly longer wheelbase, improving cabin space, while shorter front and rear overhangs ensure that it is much the same size as today's model.
Despite the shared body architecture, Porsche is nevertheless said to be introducing a new V8 and V6 gasoline engine family of its own design, rather than sharing an engine with Audi as it does in the case of the current V6.
There will also be a plug-in hybrid version and a diesel model for Europe. It is not yet clear whether there will be new transmissions to complement the fresh engines. The new engines are expected to yield improved gas mileage numbers.
Porsche is also believed to be working on a "shooting brake" wagon version of the Panamera, although this is unlikely to be sold in the U.S.
There has also been speculation concerning a two-door coupe version similar in concept to the 1977-?95 V8 928, but Porsche insiders have indicated that the company's engineering department likely has too much work going on to allow for this version.
Edmunds says: Car shoppers should expect a usefully improved Panamera that retains many of the unique features of this unusual luxury sport sedan.