Reference: GH News Post “Hybrid drivers complete run for mileage mark"

Does anyone know if the "Pulse & Glide" technique used by the Prius hypermilers work with FEH, or is the Toyota/Lexus "Hybrid Synergy Drive" system required for the non-powered glide?

The first month I used to accelerate FEH up to speed on residential roads and let up on gas pedal until tach read 1000rpm, then double tapped the brake to go into EV mode and lightly pressed pedal to get back up to and maintain speed in EV. Then I switched to a different method that seemed more fuel efficient, where I would accelerate to ~5mph higher than speed limit (up to 45mph) and release gas pedal until FEH goes into EV at about the speed limit.

The news articles of the Prius 110MPG (1,400 miles for one tank) demonstration a couple days ago indicated the Prius drivers would lightly press on pedal to deactivate the EV battery assist and glide without power. Since I don't have the NAV option that shows power flow diagram, I can't tell if I am coasting without draining battery.

Any FEH hypermilers with NAV try this technique that could fill us in?

-Dan

 

Dan,
All of the FEH's have the charge/assits gauge correct?
You should be able to look at that and position it in such a way that there is no assist or charge occuring. This would be the 'glide' described, and since the FEH uses the same planetary gearbox design it should be able to glide in the same way as the Prius, though the algorithms Ford used may not allow for it.

 

In the Prius I it's very hard to make it run in 'glide' mode, so what I've done is popped it into neutral, thus having the same effect. I don't know how easy it is to shift into and out of neutral in the FEH, but that might be the best way to do P&G if it turns out that the neutral mode isn't easy to get into.

 

I don't have the Nav system in mine to prove it, but it feels like it glides. I have kept an eye on the charge/assist gauge and I can get it to stay in the middle at up to just over 40mph on a downhill coast. Maybe I'm missing something crucial, but I think it will do it.

 

I do have the Nav system.

Just to be sure I understand what you're asking, you're talking about having forward momentum, without having drive power supplied; a powerless coasting where the ICE is off and the EV system is not contributing to forward movement or eating away at it, the vehicle is simply moving forward in a coast.

If that's what you're talking about, then yes. Not only is it possible, but I do it all the time, much more often at night when I know the light patterns and there's little to no traffic. Other than the fuel used from about 20 MPH to 40ish MPH when I accelerate to start out with, I use pretty much zero fuel after that for quite some time, where only wind resistance and friction slows the vehicle, slowly eating away at its speed. The energy flow display shows nothing, no arrows going in any direction and the ICE is off.

 

Gliding = Powerless Coast ... Yeah, that's what I'm talking about.

However, from my understanding, you cannot simply take your foot off the pedal for the glide. You need to get up to speed, let off the pedal to have ICE turn off, then LIGHTLY press the gas pedal to get the PCM to disengage the electric motor/generator for powerless coasting. Otherwise the hybrid will be in slight generation mode and actually slow down the coasting.

To answer Schwa's question - putting the FEH in neutral does not allow powerless coasting, rather it also is in generation mode (where going down a hill over 40MPH will keep the ICE on even in "neutral").

I have watched my FEH Charge/Assist gage during coast and it does not seem to stay in middle during coast with foot off the pedal, indicating slight charging (very small movement). But gage needle movement is so small, it is hard to tell if my slight pedal press has activated a PCM software command for allowing powerless gliding. That's why I think you need the NAV option to be sure.

I think the method these Prius hypermilers came up with is to get up to 45mph with ICE mild acceleration, let off pedal to turn off ICE (~40mph) and then press lightly on pedal for powerless glide until they slow to 30mph, then press pedal to reach 40mph in EV mode and then glide again ... repeat.

-Dan

 

Just to clarify, I make it sound like I troll about town using that technique, really it's just one road during my long commute that I make twice a week, coming home. Since there's virtually no traffic late at night and the timing of the lights mean that going the speed limit makes you stop at every light, I use that technique on that one road, for a space of two miles or so, and I don't try real hard to turn off the engine.

Reading about it, I'll have to try it out next chance I get, generally I don't try too hard to get the engine to turn off, we'll see how easy it is for me to do that.

Also, I know it's impossible to tell without the A/N, but when the battery is low, it seems to me that the systems do more to recharge it, which may make pulse and gliding more difficult, as it takes a more active role to recharge the battery.

The tricky part about doing the sustained part in the FEH, as I'm sure you know, is that traffic isn't that forgiving to a slow acceration like that, and to accelerate in the upper 30's to 40 in EV mode can be difficult. A good bump or getting too close to 40 and suddenly the engines on.

 

To clarify, are you able to do a powerless coast without foot on gas pedal OR are you using similar technique as the Prius hypermilers to "glide" in a FEH with slight pressure on pedal?

 

Depending on the situation, both. If I'm going to eventually stop, I take my foot off the pedal, and if I'm just trying to stay at MAX (on the MPG display) for as long as possible, I have a tiny bit of pressure on it.

 

I have been doing a lot of experimenting since I got this vehicle and I have found that I can maximize my FE by using my own version of the P&G technique. Unless I am on low-traffic interstate (rare around here), I keep the gear selector in L so that anytime I completely let off on the accelerator, I let regeneration slow me down. Even a slight amount of pressure on the pedal will keep it from regen mode so I can just use the weight of my toe to keep moving without regen braking slowing be down. I've gotten to where I can estimate how far ahead I need to let off to stop at all the lights I deal with going to work in the middle of the night. I use the brakes as little as possible since friction means wasted energy.

This tank I am on now is looking like my best yet. Showing 36 on the meter.