This guide will let you know how to use the Repulsor to Kickstart Vehicles in Halo Infinite.
It allows the Montoose to reach near full-speed within an instant and can be very useful when in a pinch.
It is not as useful on the ghost due to the poor acceleration as it has a boost for that but can still snag a splatter kill.
The chopper, though, covers a great distance.
You can also do this on the warthog, but you must remove both rear tires to make the vehicle more mobile and have less traction.