Shooting from a transport question

[Smurfs]

Theres a debate my friends are having about shooting from a transports. One of them said "there is NO exception or change to the rule for fast vehicles. Unless your codex states otherwise, models embarked on a vehicle can't shoot if the vehicle traveled more than 6" that turn. " Hes going from the rulebook 'Models firing from a vehicle count as moving if the vehicle moves, and may not fire at all if the vehicle moved at Cruising speed that turn.' Ive always thought that a fast vehicle could move up to 12" and still have people fire from it. Since Im starting with Dark Eldar, If you guys could help me figure out which is right and point me towards were in the rulebook it would say differently, it'll be greatly appreciated.

[Culven]

Your friend is correct. The Transport rules limit the shooting of embarked Units to when the Vehicle moves at Combat Speed or less. Being Fast doesn't change the distance for Combat Speed, nor do the rules for shooting with Fast Vehicles affect the embarked Unit.

[BuFFo]

You can only fire if the vehicle moved 6" or less.

At the moment, there are no exceptions to his rule for any army.

[Smurfs]

Alright, thanks for the confirmation.