MythBusters Episode 22: Boom-Lift Catapult, AC vs. Windows down

A boom-lift can potentially catapult its operator 200 feet (60 meters).

busted

When a car engine was dropped from the boom lift it barely even wobbled, much less catapulted Buster. In an attempt to duplicate the myth result, the boom lift was converted into a trebuchet, mounted on several shipping containers to give it clearance to rotate. On its first throw, it threw Buster at a steep angle towards the ground, and then collapsed between the containers, destroying it.

Running a car with air conditioning on is more fuel efficient than running with the windows down.

partly confirmed*

Tests were performed under varying conditions (55 mph versus 45 mph). The 55 mph test used a computer to estimate fuel efficiency based on air intake, not actual fuel consumption, and showed A/C was more efficient. The 45 mph test consisted of running the tank until it was empty, and showed open windows were more efficient.

* Because the original tests were inconclusive, this myth was revisited in episode 38, in which it is found that air conditioning is more fuel-efficient when the car is traveling approximately 50 mph or more. At slower speeds, windows are more fuel-efficient.