Prius Question
 

I'm posting this for a friend of mine that owns a prius and he has a question about pulse and glide with the prius.

His question was is there any benefit to neutral coasting (vs. just coasting in drive) with a prius since he assumes fuel is not being used when the car is coasting in drive after pulsing the pedal and releasing the pedal. Because the prius switches to battery power when releasing the gas pedal is there any benefit to pulse and glide with the prius?

I'm really not up to speed on how the prius works but I told him my fellow ecomodder's would defiantly have an answer...thanks!

I found neutral gliding helpful when the engine was cold.

neutral gliding in a prius or your civic? Just to clarify...specific to the prius because it used gas and battery powered engines...is neutral coasting beneficial vs. in-drive coasting?

I am by far not an expert in Prius Drivetrain, but I would think that it may not matter with a prius because the Prius should disengage the tranny when coasting, since it was designed for that. The only thing that would slow down a prius during a coast is the regenerative braking, IMO. By switching into neutral you may by pass that system, which would be beneficial, but you would also eliminate the regen braking which may not be so good.

This of course is all theoretical ...

In a prius. I found that the engine tries to warm up and runs quite a bit more then it needs to so I would put it in neutral to glide so there weren't any arrows on the screen. Pulse and glide is deff worth it in a Prius but the point is to accel and glide without any arrows, not worth it imo to try and use all electric assist all the time.

There are quite a few good guides online on proper pulse and glide techniques specifically for Prius's.

Driving the Prius normally = 55mpg, pulse and glide = 75 average

My guess was that pulse and glide in a prius is not "AS" beneficial as in a normal engine only vehicle since the engine is essentially shutting off after depressing the brake pedal and switching to battery power anyway.

I use P&G in my 4runner and obviously the benefits greatly impact my mpg but I'll have to do some more reading on the prius to see what benefits, if any, there are for doing it in the prius.

Please keep the responses coming as I'm trying to help a friend with this thread! Thanks!

The benefits would be amplified with the prius.... Even though you are using the electric motor most of the time in the city, by P&G, you use less power from the battery, therefore extending the range, thereby using the gas engine even less ...

So if there are area to explore Prius P&G, visit them, squeeze every drop out of that puppy. Nothing pisses me off more than watching a Prius blow my doors off @ 80mph on the hwy ....

Good point Trik!

My friend is at about 52mpg right now but uses no P&G...he does drive cautiously and rarely revs the engine (and never abuses the gas pedal). I know he'll never do an aero mod but he does plan to inflate tires to near-max psi soon. I'm guessing with high psi and more attention paid to P&G, slow gas pedal, etc. he would be around 60mpg.

There is actually a benefit with neutral coasting because there is no power transfer to or from the battery. Any power transfer results in a loss due to conversion efficiency. Just remember that when in neutral, you will get no regeneration when you brake. Pop it back in drive before braking to get the regen.

For more info on P&G, see my comments at the link below:
Toyota.com : Hybrid Synergy View : 2005 : Fall : Prius Marathoners Top 100 mpg

Thanks for the great info Kraus! Interesting reading even though I don't own a prius...will be a great help for my friend. Would love to see him pull 65+ mpg with no major aero mods other than psi and P&G.

I got some training from krousdb at hybridfest on just this subject.

Correct me if I'm wrong, but use of N will also prevent the engine from spinning up (adding some mechanical drag) if speed goes over 42 mph in a downhill glide.

The Prius employs "engine braking" (actually, electric motor braking) if you simply take your foot off the gas pedal in doing a "pulse and glide", so the proper technique is to apply very slight pressure to the pedal. The slight pressure prevents the ICE from coming back on (it shuts off when you start coasting). You can use the display to show when you are using electric rather than gas power and you'll soon get the hang of it.

You can drive quite a distance on "electric only" at about 38 MPH using this technique. Above that speed, the ICE seems to kick in unless you are decelerating. Getting up to 38 MPH usually requires the ICE (I've been able to accelerate only to about 18 MPH on electric only). There is a "pulse and glide" technique for that kind of city driving ... you slowly start out, then when the ICE kicks in you apply more gas to get to about 40 MPH, then back off the gas with just slight pressure on the gas pedal and enjoy the gas-free ride.

My friend inflated to near-max psi today and I've been forwarding all the great info to him. He's hooked so hopefully he can pull some good numbers and approach 65 mpg (at avg 58 mpg right now). Keep the good info coming...I appreciate all the feedback for him to use!

If you watch the energy flow screen, you want to see NO arrows anywhere for a glide. This point is with very slight pressure on the gas pedal - just above completely off. You can then pop into neutral, or hold your foot just so to maintain the glide. If you just hit it into neutral without the no-arrows first, the engine will continue to idle. You need a scangauge to see this. The built-in display looks like it's off, but it's still running. :( That detail cost me probably 2 mpg at the WFEC last month.

There's a TON of information about driving the Prius over at Cleanmpg, more than I could ever mention here. I'd suggest going and looking there.