wouldn't that macro not work since you're bars get switched out when in a vehicle?
The macro works great, but make sure that the bar you put it on is not hidden when possessing a vehicle. I use bartender and that option is in the visibility options for each bar. You just cant put it on bar 1 because that is the bar the vehicle changes when you possess it. Grab Crate is the ability you get when you get in the demolisher cannon seat.