hypermiling by coasting in neutral

This isn't true. When the battery reaches full charge (~80% - all bars green), the regenerative braking disengages, and the car will use the electric motors to spin the gas engine (with no fuel injected, only pumping air) to use up the excess energy. On my Scanguage, it's obvious because I can see the engine RPM change from 960 to about 3000 coming down hills on I-70 in Colorado. The car won't let you exceed ~80% (actual is something like 83%) state of charge on the battery.

When the battery is full and you're on a steep downhill, it's best to use the B mode to engage engine braking to keep from overheating the brakes. Better yet is to engage B at the top of very long steep downhills, to more gradually charge the batteries and reduce brake use.

 

I did realize that those are just US laws. It’s not illegal here. And I still don’t get why it would be illegal or bad idea anywhere. It’s not beneficial in a Prius but still you do safe fuel by coasting in neutral with most of cars.

Actually here in driving school they used to teach you to coast downhills in neutral to safe fuel when cars still had carbonators. In carbureted car there’s no fuel cut at engine breaking so you do safe more fuel than you would if you do the same thing with modern car.

 

US drivers are not nearly as talented.

Laws like that are (usually) written in blood, so obviously there was more than one time where somebody became an organ donor because somebody (or somebody else) forgot that when you put a vehicle in Neutral you're no longer able to use compression braking.
Over time, friction brakes heat up, and lose effectiveness.

Evidently, either this happened over and over and over again here in the US or lawmakers just sat around making up daffy laws because it's a lot more fun than golfing, chasing interns and accepting graft money.

 

Maybe the long and expensive driving school that we have here with multiple phases really helps. Normally people here just complain how expensive it is.

Second phase (now it’s actually third phase) that you have to complete within two years of getting your license has skid control on a track with own car and economical driving (with their car).

 

You lose engine braking when in neutral, even with an automatic. I once was in my auto 92 Corolla and wanted to see how fast it would coast up to down a long hill. Stopping from 80mph on a down grade with no engine braking is bad for the brakes and unsafe.
I am eager to get my Prius so I can experience no drag coasting while still having full control.

 

I think that if you practice more than:
Slow down
Anticipate what is coming so you can adjust your speed and lane choice early
Then it really amounts to distracted driving.

 

Total BS.
The car will save itself.
The driver "needs" to do nothing.

 

Maybe the smouldering brakes will ignite the overcharged, exploding battery? (Purely coffee talk)

 

at 5 o'clock?

 

I'm in favor of neutral glides to avoid energy conversion loses. In my PiP downhills some times < 62 mph or in cases where I want to slowly bleed off speed without coming to a full stop: rush hour, stale red lights, roundabouts. I'm relative flat lander in Minnesota so the glides are always less than a mile and not done on low SOC. At least for me, holding a soft glide ... engine off no regen no assist longer than a tenth is difficult. As cars use topographical, traffic and other senor data to maximize FE they will increasing auto n-glide when it's the optimal mode.

 

It is illegal because it has killed many many people, though mostly back in your grandparents' era.

Back then, brakes (nearly always drum, not disk) were weaker and much more susceptible to fading when hot, allowing the car to begin rolling too fast. Then the lack of any synchronizing mechanism often made it difficult to impossible to re-engage the transmission, resulting in a run-away vehicle and a fatal crash.

Modern vehicles, with power disc brakes and automatic or synchronized-manual transmissions, are far less susceptible to this catastrophe. So for modern passenger cars, these laws are a bit of an anachronism, a holdover from previous generations.

But it can still happen in passenger cars, and definitely does still happen in heavy trucks. That is why the long steep mountain grades have runaway truck escape ramps.