The first sentence is incomprehensible, I'm afraid. We don't tend to say that people "get a jerk", "passes on" doesn't work, and I don't know what a "speed braker" is.
The second sentence would be better as something like "Whenever I travel by car, I lie down on the back seat so that the bumpy motion of the car doesn't cause me an injury". "The jerking of the car" doesn't really work. We don't tend to say that cars jerk at all.
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