The Karl was originally assessed by Euro NCAP in 2015.  For this re-assessment, most tests have been re-done as the test protocols have changed in the intervening two years.  However, where the car and test protocols are unchanged, results have been carried over from the 2015 assessment.

The passenger compartment of the Karl remained stable in the frontal offset test.  Dummy readings indicated good protection of the knees and femurs of the driver and passenger.  Opel showed that a similar level of protection would be provided to occupants of different sizes and to those sat in different positions.  In the full-width rigid barrier test, the pelvis of the rear passenger dummy slipped beneath the lap portion of the seatbelt, and protection of this body area was rated as poor.  Protection of the chest was rated as marginal, based on dummy readings of chest compression.  Protection of all critical body areas was good for the driver dummy.  In the side barrier test, protection of all critical parts of the body was good and the Karl scored maximum points.  However, in the more severe side pole impact, the head 'bottomed out' the curtain airbag and the resulting high decelerations indicated poor protection of this body area.  Chest protection was rated as marginal based on dummy readings of rib compression.  Tests on the front seats and head restraints demonstrated marginal protection against whiplash injury in the event of a rear-end collision.  A geometric assessment of the rear seats also indicated marginal whiplash protection.

In the frontal offset test, protection of the neck and chest of the 6 year dummy was weak, and that of the neck of the 10 year dummy was poor.  In the side barrier test, protection of all critical body areas was good.  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 Karl is not compatible with i-Size restraints and, as a result, the installation check of any such restraints was deemed a fail. In addition, the large rearward-facing Group 0+/1 restraint could not be accommodated in the rear centre position.

The protection offered to the head of a struck pedestrian was mixed with areas showing good results and others, mainly on the stiff windscreen pillars, giving poor results.  The bumper provided good protection to pedestrians' legs but protection of the pelvis was predominantly poor.

The Karl has a seatbelt reminder for the front and rear seats.  A lane departure warning system and a driver-set speed limiter are available as an option but are not included in this rating.