The TT has standard head airbag curtains which act as a forgiving barrier between the driver and front passenger's upper bodies and the window and pillars. Combined with high-strength steel door beams and lower side airbags this system increases head protection in broadside collisions. The Z4 doesn't offer side airbag protection for the head.
The TT has all-wheel drive to maximize traction under poor conditions, especially in ice and snow. The Z4 doesn’t offer all-wheel drive.
The TT has a standard blind spot warning system that uses sensors to alert the driver to objects in the vehicle’s blind spots where the side view mirrors don’t reveal them. A system to reveal vehicles in the Z4’s blind spot costs extra.
Both the TT and the Z4 have standard driver and passenger frontal airbags, front side-impact airbags, driver and front passenger knee airbags, front seatbelt pretensioners, four-wheel antilock brakes, traction control, electronic stability systems to prevent skidding, post-collision automatic braking systems, daytime running lights and rearview cameras.

