I think that's kinda the parent comment's point. Just because sonar is good for indoor localization doesn't mean it's got the range for highway speeds. In fact,

I think that's kinda the parent comment's point. Just because sonar is good for indoor localization doesn't mean it's got the range for highway speeds. In fact, ultrasound on cars is for exactly this: low speed, close quarters detection. This is why backup sensors or self parking systems rely on ultrasound.