Abstract: The invention presents a sled device for testing the rollover threshold of a vehicle. The sled has a carriage that is mounted on a track. The carriage can slide upon the track from a first track location. The carriage is configured so that an actual vehicle may be placed on the carriage. When a vehicle is on the carriage, the vehicle is positioned with one side of the vehicle positioned toward the first tract location and the second side of the vehicle positioned toward the second track location. The carriage is propelled from the first tract location to the second track location by an accelerator. As the carriage nears the second track location, a decelerator slows and arrests the movement of the carriage, thereby simulating an impulse potentially sufficient to cause the vehicle to roll.