You mean that the article here was a lie?
Could a car with a JATO rocket attached speed up to 300 mph (480 km/h), become airborne, and impact with the side of a cliff?BUSTED
"Adam and Jamie could not acquire real JATO rockets from the Air Force. As such, they used 3 amateur rocket motors of equivalent power to one JATO rocket. The rockets increased the speed of the car considerably. Although no speed measurement was made, the speed was clearly nowhere near the 300 mph suggested in the myth. The car also did not become airborne.