The passenger compartment of the 508 remained stable in the frontal offset test.  Dummy readings indicated good protection of the knees and femurs of the driver and passenger.  Peugeot showed that a similar level of protection would be provided to occupants of different sizes and to those sitting in different positions.  In the full-width rigid barrier test, protection of the chest was marginal for the driver and adequate for the rear passenger, and protection of all other critical body areas was good.  In both the side barrier impact and the more severe side pole test, maximum points were scored, with good protection of all critical body areas.  Tests on the front seats and head restraints demonstrated good protection against whiplash injuries in the event of a rear-end collision.  A geometric assessment of the rear seats also indicated good whiplash protection.  The standard-fit autonomous emergency braking system performed well in tests of its functionality at the low speeds, typical of city driving, at which many whiplash injuries are caused.

In the frontal offset and side barrier tests, protection of the 6 and 10 year dummies was good or adequate for all critical body areas.  The front passenger airbag can be disabled to allow a rearward-facing child restraint to be used in that seating position.  Clear information is provided to the driver regarding the status of the airbag and the system was rewarded.  All of the restraint types for which the 508 is designed could be properly installed and accommodated in the car.

The 508 has an 'active' bonnet.  Sensors in the bumper detect when a pedestrian has been struck and actuators lift the bonnet to provide greater clearance to the hard structures in the engine compartment.  Peugeot showed that the system works robustly for different pedestrian statures and across a range of speeds.  Accordingly, the car was tested with the bonnet in the raised position.  The protection provided by the bonnet to the head of a struck pedestrian was good over almost all of the bonnet surface, with poor results seen along the base of the windscreen and on the stiff windscreen pillars.  The bumper provided good protection to pedestrians' legs at all test locations.   Protection of the pelvis was mixed.  The AEB system is able to detect vulnerable road users such as pedestrians and cyclists.  In most tests of these functionalities, the system performed adequately.

The 508 has a seatbelt reminder system for the front and rear seats.  The AEB system performed adequately in various tests of its functionality at highway speeds.  A standard-fit lane-keep assist system helps to keep the car from drifting out of lane and can also intervene in more severe emergency situations.  A camera-based speed assistance system identifies and displays the local speed limit, allowing the driver to set the speed limiter appropriately.