The passenger compartment of the ET5 remained stable in the frontal offset test. Protection of the driver dummy was good for all critical body areas.  Dummy numbers showed good protection of the knees and femurs of both the driver and passenger. NIO 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 ET5 would be a moderately benign impact partner in a frontal collision. In the full-width rigid barrier test, good or adequate protection was provided to all critical body areas, for both the driver and rear passenger. In both the side barrier test and the more severe side pole impact, protection of all critical body areas was good and the car scored maximum points in this part of the assessment. 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 found to be adequate. The ET5 has a counter-measure to mitigate against occupant to occupant injuries in such impacts and this performed well in Euro NCAP's test. 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 ET5 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.  NIO demonstrated that, if the car entered water, the doors and windows of the ET5 would remain functional long enough to allow the occupants to escape.

In both the frontal offset and side barrier tests, good protection was provided to all critical body areas for both child dummies, and the NIO ET5 scored maximum points in this part of the assessment.  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 ET5 is equipped with a direct 'child presence detection' system, which issues a warning when it detects that a child or infant has been left in the car. However, the system did not meet Euro NCAP's requirements and was not rewarded. All of the child restraint types for which the ET5 is designed could be properly installed and accommodated in the car.

Protection of the head of a struck pedestrian or cyclist was almost completely good or adequate, with poor results recorded only on the stiff windscreen pillars.  Protection of the pelvis, femur and tibia was also good at all test locations.  The autonomous emergency braking (AEB) system of the NIO can respond to vulnerable road users as well as to other vehicles.  The system performed well in tests of its response to pedestrians, with marginal performance only at night-time when a child runs from behind parked vehicles.  Performance was good in all bicyclist scenarios apart from dooring, in which the car prevents or warns against door opening if a cyclist is approaching from behind, where performance was marginal.  Good or adequate performance was seen in all tests of the NIO ET5’s response to motorcyclists.

The autonomous emergency braking (AEB) system of the NIO ET5 performed well in tests of its reaction to other vehicles.  NIO was not able to verify the car’s performance in Euro NCAP’s ‘head-on’ tests and no points were awarded.  A seatbelt reminder system is fitted as standard to the front and rear seats and the car is equipped with a system to detect driver fatigue, such as microsleep (very short periods where consciousness is lost) and distraction, such as phone use.  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.