The ID.4’s pre-crash front seatbelts will tighten automatically in the event the vehicle detects an impending crash, improving protection against injury significantly. The Ioniq 6 doesn’t offer pre-crash pretensioners.
Both the ID.4 and Ioniq 6 have child safety locks to prevent children from opening the rear doors. The ID.4 has power child safety locks, allowing the driver to activate and deactivate them from the driver's seat and to know when they're engaged. The Ioniq 6’s child locks have to be individually engaged at each rear door with a manual switch. The driver can’t know the status of the locks without opening the doors and checking them.
The ID.4 has a standard Automatic Post-Collision Braking System, which automatically applies the brakes in the event of a crash to help prevent secondary collisions and prevent further injuries. The Ioniq 6 doesn’t offer a post collision braking system: in the event of a collision that triggers the airbags, more collisions are possible without the protection of airbags that may have already deployed.
Both the ID.4 and the Ioniq 6 have standard driver and passenger frontal airbags, front side-impact airbags, side-impact head airbags, front and rear seatbelt pretensioners, height adjustable front shoulder belts, four-wheel antilock brakes, traction control, electronic stability systems to prevent skidding, crash mitigating brakes, daytime running lights, lane departure warning systems, blind spot warning systems, rearview cameras, rear cross-path warning, driver alert monitors and available around view monitors.

