If you have a Mutant Hijacker, you can steal civilian vehicles. Listed below is the amount of infrantry each one can carry.

Automobile=4
Pickup=2
RV=4
School Bus=20
Demolition truck
Take a harvester and fill it with blue tiberium, then put it in your enemy's base. I usually put it beside a building and then when they destroy it, it will blow up the building.