The bZ4X has a standard Secondary Collision Brake, which automatically applies the brakes in the event of a crash to help prevent secondary collisions and prevent further injuries. The Leaf 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.
The bZ4X has all-wheel drive to maximize traction under poor conditions, especially in ice and snow. The Leaf doesn’t offer all-wheel drive.
Both the bZ4X and Leaf have rear cross-traffic warning, but the bZ4X has Parking Support Brake (automatically applies the brakes) to better prevent a collision when backing near traffic. The Leaf’s Rear Cross Traffic Alert doesn’t automatically brake.
Both the bZ4X and the Leaf have standard driver and passenger frontal airbags, front side-impact airbags, driver and front passenger knee airbags, side-impact head airbags, front and rear seatbelt pretensioners, front wheel drive, height adjustable front shoulder belts, four-wheel antilock brakes, traction control, electronic stability systems to prevent skidding, crash mitigating brakes, lane departure warning systems, blind spot warning systems, rearview cameras, rear cross-path warning and available around view monitors.
Side impacts caused 23% of all road fatalities in 2018, down from 29% in 2003, when the Insurance Institute for Highway Safety introduced its side barrier test. In order to continue improving vehicle safety, the IIHS has started using a more severe side impact test: 37 MPH (up from 31 MPH), with a 4180-pound barrier (up from 3300 pounds). The results of this newly developed test demonstrates that the Toyota bZ4X is safer than the Leaf:
| 
 | bZ4X | Leaf | 
| Overall Evaluation | GOOD | ACCEPTABLE | 
| Structure | GOOD | MARGINAL | 
| 
 | Driver Injury Measures | |
| Head/Neck | GOOD | GOOD | 
| Head Injury Criterion | 105 | 211 | 
| Neck Tension | 156 lbs. | 201 lbs. | 
| Neck Compression | 22 lbs. | 67 lbs. | 
| Torso | GOOD | GOOD | 
| Shoulder Deflection | .51 in | 1.14 in | 
| Shoulder Force | 134 lbs. | 245 lbs. | 
| Pelvis | GOOD | ACCEPTABLE | 
| Pelvis Force | 870 lbs. | 1093 lbs. | 
| Head Protection | GOOD | GOOD | 
| 
 | Passenger Injury Measures | |
| Head/Neck | GOOD | GOOD | 
| Torso | GOOD | GOOD | 
| Shoulder Deflection | .63 in | 1.54 in | 
| Shoulder Force | 223 lbs. | 335 lbs. | 
| Torso Max Deflection | 1.18 in | 1.38 in | 
| Pelvis | GOOD | ACCEPTABLE | 
| Pelvis Force | 647 lbs. | 937 lbs. | 

