Consulate Dreadnought

If a permanent becomes a copy of a Vehicle, the copy won’t be a creature, even if the Vehicle it’s copying has become an artifact creature.

Once a Vehicle becomes a creature, it behaves exactly like any other artifact creature. It can’t attack unless you’ve controlled it continuously since your turn began, it can block if it’s untapped, it can be tapped to pay a Vehicle’s crew cost, and so on.

Vehicle is an artifact type, not a creature type. A Vehicle that’s crewed won’t normally have any creature type.

You may activate a crew ability of a Vehicle even if it’s already an artifact creature. Doing so has no effect on the Vehicle. It doesn’t change its power and toughness.

For a Vehicle to be able to attack, it must be a creature as the declare attackers step begins, so the latest you can activate its crew ability to attack with it is during the beginning of combat step. For a Vehicle to be able to block, it must be a creature as the declare blockers step begins, so the latest you can activate its crew ability to block with it is during the declare attackers step. In either case, players may take actions after the crew ability resolves but before the Vehicle has been declared as an attacking or blocking creature.

If an effect causes a Vehicle to become an artifact creature with a specified power and toughness, that effect overwrites the Vehicle’s printed power and toughness.

Each Vehicle is printed with a power and toughness, but it’s not a creature. If it becomes a creature (most likely through its crew ability), it will have that power and toughness.

Any untapped creature you control can be tapped to pay a crew cost, even one that just came under your control.