The other team craves more power and uses a moped engine. But turning off an engine you've worked hard to get started can prove problematic. The producers have asked teams to retrieve two cars carelessly parked underwater. One team decides to attach water-filled barrels to the car, then fill them with air, floating the car to the surface. The other team builds a huge floating barge with a giant crane to pick the car up.
Diagrams reveal that they'll run into problem with the machines weight, and center of gravity.
In this episode, the teams have to build a wheel-free vehicle to carry all of them, plus one very heavy safe, through a muddy and bumpy obstacle course. The other team decides to go with a hydraulic machine that can only be described as a walking dinner table.