Premier Date: May 13, 2009
Adam and Jamie set fire to a car with gasoline and measured the temperature with a thermographic camera, eventually determining that the blaze reached 1,400 °C (2,600 °F), enough to melt the aluminum bumper but surprisingly unable to make the bumper shock explode. Suspecting that unfocused flames might have caused the explosion to fail, back in the shop they subjected several bumper shocks to directional heat from an oxyacetylene torch at various spots. However, all shocks lost pressure in one way or another before they could explode. During the episode, the MythBusters interviewed an Oakland firewoman who indeed suffered bumper knee-capping. But in her accident, the bumper flew only 15 feet (4.6 m) instead of 50 feet as alleged in the myth. Finally, Adam and Jamie simulated a 50-foot bumper blast using a delicately engineered rig consisting of two pistons packed with gunpowder and wet sand and an electric ignition system, which demonstrated the improbability of such a blast under normal conditions.
The Build Team first attempted to test the myth by having trained horse archers firing at a foam target at varying speeds. However, they were unable to get consistent data because the three archers they tested all rode at different speeds, fired their arrows at different distances, and had varying arrow velocities. For a more conclusive test, the Build Team obtained a Jeep and mounted a crossbow on the top. They then fired arrows at a large foam target while stationary and then while the Jeep was driving at 40 miles per hour (64 km/h), in both cases from a fixed distance of 60 feet (18 m). While the arrows fired while the Jeep was moving did penetrate deeper into the target, they did not penetrate twice the distance of the arrows fired while stationary, busting the myth.