and the car will use it when appropriate. It'll engage once above 30-35 mph, any time I'm not getting on the car. I've actually found that acceleration, above 40 mph, is better when OD is engaged. The computer in the Z is very good at picking the best gearing for the moment. I'll only manually choose a low gear, when I know I don't want the car to up-shift at an in opportune moment.