The IONIQ 5 receives a B grade because the audio signal for the second-row centre seat, which does not have occupant detection, only activates if the seatbelt is fastened and then unfastened. From the IONIQ 5's owners' manual:
"Rear passenger's seat belt warning
For rear left and right side seat
• As a reminder to the rear passenger, the rear passenger's seat belt warning lights will illuminate for approximately 6 seconds each time the START/STOP button is in the ON position regardless of belt fastening.
• If you start to drive without the seat belt fastened or you unfasten the seat belt when you drive under 20 km/h 12 mph), the corresponding warning light will continue to illuminate until you fasten the seat belt.
• If you continue to drive without the seat belt fastened or you unfasten the seat belt when you drive 20 km/h (12 mph) and faster, the seat belt warning chime will sound for approximately 35 seconds and the corresponding warning light will blink.
• When the seat belt is unfastened during driving, the warning lights will illuminate when the speed is under 20 km/h (12 mph).
• When the speed is 20 km/h (12 mph) and faster, the warning light will blink and warning chime will sound for approximately 35 seconds.
For rear center seat
• As a reminder to the rear passenger, the rear passenger's seat belt warning lights will illuminate for approximately 6 seconds each time the START/STOP button is in the ON position regardless of belt fastening.
• If the seat belt is not fastened when the START/STOP button is turned on, the seat belt warning light will illuminate for approximately 70 seconds.
• If you start to drive without the seat belt fastened or you unfasten the seat belt when you drive under 20 km/h (12 mph), the corresponding warning light will continue to illuminate for approximately 70 seconds.
• If you continue to drive without the seat belt fastened or you unfasten the seat belt when you drive over 20 km/h (12 mph), the seat belt warning chime will sound for approximately 35 seconds and the corresponding warning light will blink.
• If the rear door is opened or closed under 10km/h (6 mph), warning light and warning sound does not work even if driving over 20 km/h (12 mph)."
