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So, what is wrong with coasting downhill to save gas? I do it all the time, but heard you guys lambaste it on the show.

  1. unsafe
  2. illegal
  1. ineffective

(Oh, - and no one here is “you guys.” If you want to send a note to the show hosts then you need to find the right link for that).

is is illegal in every state and how would it be unsafe?

Because if someone’s coming up quickly behind you you can’t floor it and get away. And if something runs in front of you the engine isn’t helping you slow down. And if your brakes fail, the engine isn’t helping you slow down.

That’s why it’s unsafe.

Modern engines use next to no fuel when in gear going down hill. They shut off the fuel supply because it isn’t needed, since the rotating wheels turn the engine. But if you disconnect the engine from the wheels by coasting in neutral, the engine has to keep using fuel to stay on.

That’s why it’s not only unsafe, but wastes fuel.