Posts on hyper-miling suggest shifting one's car into neutral to coast as frictionlessly as possible on little gas. The method works - I've used it effectively with my '94 Chevy. But with the prius, putting the car into neutral eliminates the ability to recharge the battery via regenerative breaking (which seems to kick in as soon as you take your foot off the acceleration in Drive). So what makes the most sense from a fuel economy perspective?
Rolling freely is better than regenerating, but if you have to brake make sure your back regenerating.
Thanks. Back regenerating means the "B" gear, correct? Are there speeds at which that's not good for the car (such as going downhill at 60 mph)?
No, B is for engine braking when going down steep hills to slow car. For normal driving just leave car in D. When you want to coast just lift your foot slightly and keep it rolling with out gas and without regeneration. Then when you stop you will be regenerating, then you will be ready to go again just give it gas and go.
Read some of this! The one and only Prius Plug-in FAQ! | PriusChat This should answer a lot of your questions!
keep the bar on the hsi at or just to the right of regen. that's close enough to coasting for true hypermilers. that way, when you want to slow down, you can just let off the pedal a bit and regen, instead of trying to switch from neutral to drive and calibrate your foot as well.
Gliding in neutral should be part of the "learn to drive the PIP manual." This car rolls forever. I'll build up speed in neutral just to gain breaking regen. Shifting from "D" to "N" is like cutting the cord. I often wonder how much the regen brakes and transmission hurts MPG.
If you are building up speed in neutral, then you are going downhill and should be charging the battery. The regen system is responsible for approximately 1/3 of the Prius overall mileage efficiency. Shifting to neutral does a lot more than just disable the regen. You should probably be wondering how much better your mileage would be if you let the hybrid system do its job.
And at the risk of sounding like a wuss, coasting in Neutral is a vehicle code violation in some states, such as California.
With the Prius at least, I'd leave it in Drive, all the time. B mode (increased engine braking) is worthwhile only if you're running down an extremely long/steep hill, to the point that the battery will not charge any more and the car switches over to regular brakes, and they start to overheat. I don't think I've had the experience. I recall rolling into Whistler from the east, a very long downhill run. Thought I'd try B mode. Engine revs shot up, alarmingly. I switched back to drive, revs went down, and the car continued to charge. Even if you do exceed the charging limit, I've heard the car will do a bit of B mode, without you even selecting it. And shifting to Neutral seems to make little different to rolling resistance in my experience. Plus no charging.
Thanks for all the advice. I think I'm going to experiment with Neutral. Unless I'm looking to slowly and gradually decelerate, I'm going to put the car in Neutral and coast with as little resistance as possible. I understand that doing this is the same as hitting the acceleration pedal ever-so-slightly, but I actually find that more difficult (and uncomfortable) than simply going into neutral. I'm used to driving this way (that is, shifting between neutral and drive), and am happy to go back to it. If I notice anything appreciable in terms of fuel efficiency, I'll report back.
Wow, going against a unanimous group of replies. You've got some nerve... Just kidding. I'm on the other side but good luck all the same.
To those saying it's bad because it doesn't charge: consider this. In D, when you let off the accelerator, the car starts doing the equivalent of engine braking, but with regen. That means it slows the car down more so than if you just coasted. Now, if you wanted to maintain speed instead of slowing down, you'll have to speed up again. Given the laws of physics, it should be obvious that regen+reaccelerate is going to be less efficient than just straight up coasting.
Agreed...except on a hybrid the ICE shuts off when power demand is low. Hardcore tactics for pulse and glide involve an engine kill switch in combination with neutral. The Prius may or may not turn off the ICE depending on conditions when neutral was triggered.
actually, when you let off the accelerator all the way. when you let off partially, you can glide just like in neutral.
Yeah. I hadn't really thought about, but I think I do sometimes subconciously ride the gas pedal slightly, for a better coast, preventing charging. IMHO, that's easier and more convenient than shifting to Neutral.
