As commander of a vehicle, I am unable to tell my driver to move ahead Slow/Fast other than Fast through pressing Forward twice. I have rebound the fast and slow keys to multiple options, but none of them have any effect. However, the default CTL+w still works for Slow. I use ESDF for movement, so have rebound all of the controls and use W for various weapon functions, but stumbled onto the fact that CTL+w still works for Slow (and therefore the only way to get the vehicle to move slowly other than through manual/analog control). If you have rebound CTL+w and/or SHF+w to something else, these no longer work for Slow and Fast respectively. This means your only options are to use the Forward command once for Normal, twice for Fast, and there is no way to go Slow through these key commands.