"Road and mud aren't exactly all terrains. Somebody ought to build a vehicle that actually goes over all terrains." — Phineas
After watching a commercial for an all-terrain vehicle, Phineas Flynn decided that he and Ferb Fletcher could build a better model - one that could drive on literally any type of surface. It got built with an electromagnetic motor, super rubber tank treads, a high-speed ceramic body, hydraulics, an old remote control, and a rocket mode ("The Secret of Success").