Adult occupant
The passenger compartment of the 508 remained stable in the frontal impact. Dummy readings indicated good protection of the knees and femurs of the driver and passenger. Peugeot was able to show that a similar level of protection would be offered to occupants of different sizes and to those sat in different positions. Dummy readings of the ribs indicated adequate chest protection in the side barrier test, with good protection of the other critical body areas. In the more severe side pole test, chest protection was marginal. The seat and head restraint offered good protection against whiplash injuries in a rear-end impact.

Child occupant
Based on dummy readings in the dynamic tests, the 508 was awarded maximum points for its protection of the 3 year infant. The front passenger airbag can be disabled to allow a rearward facing child restraint to be used in that seating position. The switch is clearly labelled and unambiguous information is provided to the driver regarding the status of the airbag. The system was rewarded by Euro NCAP. Permanently attached labels clearly warn of the danger of using a rearward facing child seat in that position without first disabling the airbag.

Pedestrian
The protection provided by the bumper to pedestrians' legs was good in most areas tested but poor in some. The front edge of the bonnet offered poor or marginal protection. In most areas likely to be struck by a child's head, the bonnet offered good protection. However, in those areas likely to be struck by an adult's head, the bonnet provided poor protection.

Safety assist
Electronic Stability Control is standard equipment on the 508. A driver-set speed limitation device is optional on basic grade variants in a few European countries but is otherwise standard equipment. Sales as standard are expected to exceed Euro NCAP's 2011 fitment requirement (95%) and the system was rewarded. A seatbelt reminder is standard for the driver, front passenger and rear seats.