Coasting in Neutral Advisable?

Balboa · 11-14-2011, 04:48 PM

I was wondering if coasting in neutral is ok for long down hills. It's not bad for the car right?

Eli · 11-14-2011, 05:12 PM

This always ends up in a huge debate.. lol. Just depends on what you were taught.

It's not bad for the car, nope. Be advised that this practice is against the law in many(most?) states - though of course the chances of you getting ticketed for it are slim to none.

In my opinion, coasting in neutral is improper manual driving technique. You should always be in the proper gear for your speed. This is the reason for the laws against it. I understand that many people were not taught this.

Also be aware that if the engine is idling while you're coasting in neutral, you're wasting fuel, even though the FCD will still be at 150+MPG. In contrast, when the wheels are driving the engine, the fuel injectors are turned off.

It can also be seen as inefficient because it's wasted regen opportunity, unless your pack is completely topped off that is.

**Rainsux** · 11-14-2011, 05:42 PM

I do it a LOT, 4-5 times every morning going to work, and anytime I have a shot at a downhill section. But I'm using FAS and the engine isn't running.

These laws were written for normal cars that lose their power steering and power brakes when the engine is shut off. This doesn't affect the Insight because it has electric power steering and the engine restarts briefly when the vacuum gets too low to power the brakes.

But you ARE wasting gas idling rather leaving it in gear where the injectors are shut off. Try just putting it in 5th and coasting, probably getting some regen as well. Or shut the engine off.

Sam

diamondlarry · 11-14-2011, 06:04 PM

On my 9 mile trip to work, right at 3 miles are spent coasting up to the stops...engine off. Speed by the time I reach the stops...usually under 10 mph. On the summer mornings with temps in the 60's and 70's, this approach allowed me to consistently get over 100 mpg (average of 115) with a best of just over 134 mpg. SoC was usually 19-20 bars so most of the time regen wasn't possible anyway.

InsightGary · 11-14-2011, 08:09 PM

If you have a manual, turning off the engine and coasting (FAS) is the number one way
to get good numbers. It won't hurt the car, it won't hurt you if you know what you are
doing. The law was written in the dark ages when car brakes couldn't be counted on,
engine compression was the only way to slow down.
For short decels like coming to a stop sign, do a regen but for any thing longer, shut
it off and get the infinite mpg.
Gary