The Countryman SE has a standard PostCrash iBrake, which automatically applies the brakes in the event of a crash to help prevent secondary collisions and prevent further injuries. The Ariya 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.
To provide maximum traction and stability on all roads, Full-Time Four-Wheel Drive is standard on the Countryman SE. But it costs extra on the Ariya.
Both the Countryman SE and Ariya have rear cross-traffic warning, but the Countryman SE has Brake Intervention (automatically applies the brakes) to better prevent a collision when backing near traffic. The Ariya’s Rear Cross Traffic Alert doesn’t automatically brake.
Both the Countryman SE and the Ariya have standard driver and passenger frontal airbags, front and rear side-impact airbags, driver and front passenger knee airbags, side-impact head airbags, front seatbelt pretensioners, 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.

