[scorpio_rocks]

I believe that the only troops ever trained to fight from their vehicles were early war panzergrenadiers - they quickly stopped doing it and emphasised quick transition between travelling in vehicles and fighting on foot.

Many vehicles, to this day, are provided with "firing ports" although most forces do not use them - the British always remove the ports and add extra armour (eg mastiff) as they believe there is NO tactical benefit of passengers firing from the vehicle.