Maybe they can use the Logan's run solar car sound as a stand in for engine noise. Or grippier tires too but then that gets loud on the highway. Maybe a certa

Maybe they can use the Logan's run solar car sound as a stand in for engine noise. Or grippier tires too but then that gets loud on the highway. Maybe a certain frequency would be noticeable (rumble) at low speeds but ultrasonic at high speeds?