how to use vehicles in lego batman (ds)

I have finally unlocked the first levels vehicle (an armoured tank). When i go to the small computer it is there but I have no idea where to find it to use it? I hope someone can help.

Vehicle controls:D-Pad to move, press down to slow the vehicle.
X is to use the Boost rockets, you need Boost Energy to do so.
Y is to shoot.Does this answer your question? If you need more help you should post in the video game help section.

Wait, there are vehicles in this game?
Wow.