There’s decent space for a tall driver and front passenger, despite the 508's sleek, coupé-like roofline. However, the news isn't as good in the rear.
Yes, there’s just enough space for a six-footer to fold their legs in behind a lanky driver, but head room is so limited that it's basically a child and short adult-only zone, unless people are prepared to travel with their heads cocked to one side.
Similarly, the boot is on the small side by the standards of the executive car class, with room for just seven carry-on cases, compared with the eight that you'll get in a Volkswagen Arteon and the 10 that a Skoda Superb can swallow.
At least the 508's hatchback, rather than a saloon-style body, gives it a large boot opening that helps with loading.
In addition, you can fold the rear seats down in a 60/40 configuration by pulling toggles positioned just behind the headrests, although the seats don’t lie completely flat.