The i4’s pre-crash front seatbelts will tighten automatically in the event the vehicle detects an impending crash, improving protection against injury significantly. The Prius Prime doesn’t offer pre-crash pretensioners.
The BMW i4 has standard driver and front passenger side knee airbags mounted low on the dashboard. These airbags helps prevent the driver and front passenger from sliding under their seatbelts or the main frontal airbags; this keeps them better positioned during a collision for maximum protection. Knee airbags also help keep the legs from striking the dashboard, preventing knee and leg injuries in the case of a serious frontal collision. The Prius Prime doesn’t offer knee airbags.
The i4 offers all-wheel drive to maximize traction under poor conditions, especially in ice and snow. The Prius Prime doesn’t offer all-wheel drive.
Both the i4 and the Prius Prime have standard driver and passenger frontal airbags, front side-impact airbags, side-impact head airbags, front seatbelt pretensioners, four-wheel antilock brakes, traction control, electronic stability systems to prevent skidding, crash mitigating brakes, post-collision automatic braking systems, 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.
The BMW i4 weighs 982 to 1557 pounds more than the Toyota Prius Prime. The NHTSA advises that heavier cars are much safer in collisions than their significantly lighter counterparts.

