The passenger compartment of the #3 remained stable in the frontal offset test. Dummy numbers showed good protection of the knees and femurs of both the driver and passenger. smart showed that a similar level of protection would be provided to occupants of different sizes and to those sitting in different positions.  Analysis of the deceleration of the impact trolley during the test, and analysis of the deformable barrier after the test, revealed that the #3 would be a benign impact partner in a frontal collision. In the full-width rigid barrier test, protection of all critical body areas was good for the driver and good or adequate for the rear passenger. In the side barrier test, protection of all critical body areas was good and the #3 scored maximum points in this part of the assessment.  In the more severe side pole impact, protection was good or adequate for all critical parts of the body.  Control of excursion (the extent to which a body is thrown to the other side of the vehicle when it is hit from the far side) was marginal. The #3 has a counter-measure to mitigate against occupant to occupant injuries in such impacts. In Euro NCAP’s test, the heads of the driver and front passenger hit each and the protection was rated as poor.  Tests on the front seats and head restraints demonstrated good protection against whiplash injuries in the event of a rear-end collision.  A geometric analysis of the rear seats also indicated good whiplash protection.   The #3 has an advanced eCall system which alerts the emergency services in the event of a crash.   The car also has a system which applies the brakes after an impact, to avoid secondary collisions.  smart demonstrated that if the car entered water the doors, if locked, could be opened within two minutes of power being lost but not that electric windows would remain functional long enough to allow occupants to escape.

In both the frontal offset and side barrier tests, good protection or adequate was provided to all critical body areas for both child dummies.  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.  The #3 is not equipped with 'child presence detection', a system which issues a warning when it recognises that a child or infant has been left in the car. All of the child restraint types for which the #3 is designed could be properly installed and accommodated in the car.

Protection of the head of a struck pedestrian or cyclist was predominantly good or adequate, with some poor results recorded on the stiff windscreen pillars.  Protection of the pelvis was mostly good, while maximum points were scored for protection of the femur, knee and tibia.  The autonomous emergency braking (AEB) system of the smart can respond to vulnerable road users as well as to other vehicles.  The system performed adequately in tests of its response to pedestrians but scored no points for protection of those behind the car who are vulnerable when it is reversing. The system scored highly in tests of its reaction to cyclists, including some points for dooring, in which the car prevents or warns against door opening if a cyclist is approaching from behind.  Similarly, the AEB system performed well in all tests of its response to motorcyclists.

Overall, the autonomous emergency braking (AEB) system of the smart #3 performed well in tests of its reaction to other vehicles and scored some points in the head-on test scenarios.  A seatbelt reminder system is fitted as standard to the front and rear seats and the driver status monitoring system can detect various forms of driver inattention as well as symptoms of fatigue.  The lane support system gently corrects the vehicle’s path if it is drifting out of lane and also intervenes in some more critical situations.  The speed assistance system identifies the local speed limit, and the driver can choose to allow the limiter to be set automatically by the system.