"Pulse and Glide" Survey

Meh, close to 5% in town (using hills), 0% on highway. There's too much in-town traffic and since it gets me only a few extra mpg, it doesn't save me much and it's not worth risking safety or trying so hard to push high mpg, especially in the winter. I'd rather just use the car and whatever my mpg is, that's it.

 

i use to use it all the time off the highway, pre pip. now only when in hv mode.

 

My Prius --
City: 10-30% depending on traffic density. Heavy stop-and-go traffic increases my rate, when P&G can be coordinated with the traffic movements.
Highway: 0%. It just isn't worthwhile above the threshold speed where the ICE must spin, which is below highway speed on my Gen3. If I shifted to a Gen4, that answer would change.

My stick-shift Subaru:
Highway: 0-25%, depending on terrain. It is coordinated with terrain, essentially none on flat ground, plenty on rolling hills.

 

I don't do it much. For my work commute I generally try to keep up with the traffic. One thing I do though is try to keep the hybrid bar low in the hybrid Eco section (first section on the EV bar) if I am on battery alone. If I have to accelerate under battery I usually just hit the pedal a little harder to start the ICE for a few seconds then back off and go battery power again. So I guess that's kind of like P & G. I usually do that on slower roads, like others have said not much benefit at highway speed to me.

 

I don't really know what else to call it that doesn't take an entire sentence to explain

 

Can you define "pulse and glide" for us newbies? thanks

 

Its a technique used to drive a hybrid. Basically, from a dead stop, one accelerates hard to get slightly over the speed limit, then watches the bars on the screen to keep the ICE from turning on again. The goal is to use the ICE to get to the speed limit fast, then using the electric motor to drive. I've tried it, and it takes the fun away from just good ol'fashioned driving for me.

 

So, I think I understand: get to speed, then let go of accelerator, thus starting regeneration, then press slightly on accelerator to use only electric power? I do that all the time. I would say 95% of city driving. On the highway, I cannot get it to work. I guess my foot is not delicate enough.

 

The simplest way I can put it is that the way car engines (at least gas burning internal combustion engines) tend to work, they are more efficient running harder for short periods (pulse) then at minimum speed (gliding) for longer periods then they are when you run them at a constant medium speed the whole time. This is magnified in a hybrid because instead of idling during the glide the engine can be completely off.

So the result is as stated above, short bursts of acceleration followed by long stretches of EV. The bigger the speed difference you can manage (say accelerating to speed limit + 5, then letting it fall to speed limit -10) the less gas you use. The trade off is you become erratic in traffic when doing it with a big speed difference instead of steady and predictable, which is generally considered safer.

 

Yep, highway won't work. I get my worse mpg on the highway and better gas mpg in city stop and go driving.

 

Since the engine can't shut off over 42-46 mph (46 if accelerating, 42 if slowing down), you lose some of the benefit. It also takes more energy to accelerate to higher speeds and you lose some benefit there too.

 

So, is pulse and glide OK on the ICE, or does it stress it out too much?

 

The Prius generally protects its ICE from stress. The redline is supposed to be 5200 rpm but I've never seen mine get over 4200 even at full throttle. It doesn't hurt it to pulse and glide.

Edit: It should be noted that above a certain RPM the engine is out of its highest efficiency band and you lose the advantage from the pulse. Our member bwilson4web has made full graphs and charts about this. In general, I would keep it under 3200 rpm, which is roughly the far end of the HSI bar (the max of the PWR zone). For max efficiency some don't go into the PWR zone at all, but it's too slow for me if I don't go into it.