“I don’t know of anything that says you can’t do that,” said Krista Hedstrom.

The Washington State Patrol trooper said she learned to drive doing it, and I’d just commented on how a lot of people ask me about it when I tell them I’m hypermiling.

“Do you coast down hills?”, people ask.

To the RCW book and online reference Hedstrom went.

“I’ve never had to look that up,” she said.

Sure enough, RCW 46.61.630 spells it out:

(1) The driver of any motor vehicle when traveling upon a down grade shall not coast with the gears of such vehicle in neutral.

(2) The driver of a commercial motor vehicle when traveling upon a down grade shall not coast with the clutch disengaged.

Now, let’s be clear, I’m not trying to make Trooper Hedstrom look silly for not knowing that one off the top of her head. If you look at the “Rules of the road” section in the state’s RCW database, you’ll quickly realize that no one probably knows EVERY traffic law. And realize that most of the laws you see have sub, sub-sub, and maybe sub-sub-sub laws.

I went to Hedstrom’s office this morning because I’ve wondered, and some have debated, what’s legal and what’s not, when it comes to hypermiling?

Laws vary from state to state, and I get the feeling a common sense approach is the best way to go about things.

Some more “advanced” techniques are no-brainers, when it comes to safety and legality. Drafting behind a semi? Take a guess. Cutting off your engine while coasting? If you can’t coast in neutral, again, take a guess?

“If you think in your mind it’s a bad idea, it probably is,” Hedstrom said.

During this experiment, I’ve agreed not to do anything illegal or crazy, so I suppose I’ll “coast” down hills in 6th. Even with that, there’s debate over whether in-gear engine braking or coasting in neutral uses more fuel. (Anybody have an answer?)

Every time we get behind the wheel, we take a calculated – or sometimes random – dose of risk in breaking or bending the rules of the road.

If you speed, you know you’re risking a ticket, or increasing the likelihood of a crash. One could say the same about coasting in neutral.

You exercise discretion in your driving style. Police exercise discretion in writing tickets.

“We don’t really have a choice what we pay for gas,” Hedstrom said.

When you can, choose wisely.

6 thoughts on “HYPERMILING: Is That Legal?

  1. I still would just say, why bother with risky methods. Just cut them out and drive safely. There are plenty of safe and unquestionable hypermiling techniques, so why not just use those.

  2. Yes coasting while in gear uses more fuel. I can prove it. I own a Scanguage II. It shows fuel flow, and there is a difference from coasting in gear vs coasting with clutch pushed in.

  3. Illegal…hmmmm…hadn’t thought about that possibility. Although, I guess thinking of it now, it makes sense that tailgating might be illegal, as well as turning off the engine while coasting. I’m sure our Interstate highways (a.k.a. “freeways” in other states) also have minimum MPH as well as max. Maybe I ought to investigate SD laws to find out what could cause problems here. I am sticking to techniques that I feel are relatively safe, so don’t think legality should be a problem, but then again you never know.

    Thanks for the food for thought!

  4. When I was low on fuel and a long way from a gas station, I coasted in neutral every chance I got, thinking it was sensible, not against the law.

    Riding a recumbent trike I coast as fast as I can go downhill …not glancing at the speedometer, total focus on the road ahead and keeping my hands steady and soft around the handlebars.

    Is that illegal?
    Sharon O’Hara

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