This time, though, the spy photographers have managed to snap a photo of the car's interior. As expected, the new range-topping four-door has an i-Cockpit cabin that's heavily influenced by jet fighters.
Like the 3008 crossover, the 508's interior has a high-mounted digital instrument display, a pistol-grip gear selector, and a leather two-spoke steering wheel with a flat top and bottom.
Although there's a shroud over the centre of the dashboard, we expect a free-standing tablet-style infotainment screen and a row of metal-like buttons to be hiding underneath, and heavily angled towards the driver.
The contrasting yellow stitching and bolstered seats suggest the prototype pictured here might be a GT or GT-Line model.
Externally, this latest prototype doesn't reveal anything we didn't see with the car spotted at the beginning of June. Unlike that earlier car, though, this vehicle only has a single exhaust tip.
Despite the head-to-toe camouflage, we can see the new 508 will have a sportier, yet still elegant and very French, suit. The car's new fastback-style rear helps to deliver a visual dynamism missing from today's sedan, and will likely mean the new car is positioned against the likes of the Volkswagen Arteon.
Although we can't see too many of the car's styling details, the new 508 seems to be heavily inspired by the 2014 Exalt concept. Both the prototype and the concept share a sharp crease and bulge above the rear wheel arch.
The second-generation 508 will use the company’s EMP2 platform, with motivation coming from a range of turbocharged petrol and diesel engines, as well as a plug-in hybrid option.
Befitting its role as a flagship vehicle, it has been confirmed the new 508 will be available with a selection of driver assistance and autonomous driving technologies, including hands-free steering, and automated braking in traffic, on highways and during parking.