To run out of gas means to lose one's energy or motivation, and in this context it is implied that it would be dangerous to do so on the freeway.
Consider the staetement "Don't get exhausted and lose your motivation on the freeway, its dangerous, a lot of unsavory characters out here.". Based on this statement, is "Dont run out of gas on the freeway, its dangerous, a lot of unsavory characters out here." a true statement? Yes/no/unknown