My first attempt at hypermiling = FAIL

I could see situations where the plug in Prius would help my daily (65 - 70 mile round trip) commute, even if I couldn't charge at work. There are spots where my slow and go becomes stop and go and having the PIP would help with this. Otherwise, I'd probably use it for assisting in climbing the one hill I have to overcome, thus preventing the low mileage I get on this portion of my commute.

On the weekends....it would be solid gold! All these short trips requiring the engine to fire up and warm up the catalytic converter....ugh.

 

If the ICE is spinning, you ain't gliding

 

I avoid the use of the term Warp Stealth around the newbies.

 

The only drawback is you would go from being one of the top FE guys to one of the lowest. That is the beauty of the PIP for those with short commutes. They go from the lowest FE to the highest.

In my case I went from 70mpg bragging rights to being embarrassed by the same mileage. lol

 

As you learn the car, remember that the engine can spin yet not consume fuel. This occurs when trying to glide at speeds higher than 46mph (or 42mph). In such cases your RPM will equal 960 or more commonly, 992.

 

I hear ya, but I press my point to emphasize that the advantage or P&G stems mostly from savings on ICE spin.

I'm glad to see people interested in improving their personal fuel economy, but spending lots of efforts on tricks before learning to slow down and minimize brake use is missing the low hanging fruit.

 

Yep. Energy is consumed, although not petrol. The petrol comes later, to make up the energy spent ..

If unclear, the energy spend is either battery or kinetic.

 

Not required.

MPG tells you how much petrol is consumed;
RPM above zero implies energy wasted through friction. Years ago Hobbit measured about a 2 kW power drain if the ICE is spinning.

 

Agreed but in the grand scheme of things it is fairly insignificant for day to day driving. My point in bring this to attention is that there may be cases where one cannot travel at low enough speeds to keep the ICE from spinning. On my daily commute the freeway speed limit is 65mph and the decline lasts for 8+miles. I cannot travel at below 60mph without becoming an impediment to other traffic. Warp stealth is great in this instance.

 

However, under special circumstances high speed situation (+50 mph), when the electric motors is on and the ICE will spin at 992 RPM but it will not be burning gas, i.e. GPH=0.0. This is very difficult to induce this mode on the Prius - I can only do it once in a while. Eventually - u will burn too much electricity and the ICE will start up again...very strange stuff. Because it burns electricity and relies too much on the HV Battery's state of charge - I don't actively seek to induce the Prius into this mode because - rebuilding up the SoC can lower the car's overall MPG.

 

Walter, you are describing F8L's 'warp stealth.'

Warp stealth insures that the ICE is not operating in an inefficient range, but I cannot think of another advantage. Sometimes it is a bad idea if the battery is draining to maintain the state, because then as Walter says recharge may be at an inopportune time so far as efficiency goes. Remember, the Prius cares for the battery FIRST.

F8L's long downhill does not really give him much choice in the matter of what mode to pick, but he does not feel much pain because the ICE spin is driven by potential energy. Make no mistake though -- that potential energy was wasted, in the sense that speeds over 45 mph required ICE spin. In terms of energy loss, warp stealth is pretty similar (but somewhat worse) to coasting. Coasting is nice, but gliding is a whole lot better

If the long downhill requires a constant battery drain, I would instead consider a short ICE fuel pulse to go a little faster than I want, and then shoot for no battery flow the rest of way down.

 

I agree that gliding is best but at those high speeds your only real choice is coasting with regen or warp stealth. I feel it is better to warp stealth and allow your speed to increase as dictated by the slope and warp stealth for as long as you can until you come back down to your desired speed. You cover much more ground that way, especially if there is a small hill or two coming up. In this way you can DWL on those small hills.

I could be wrong but I feel it is efficient enough that we are splitting hairs.

I will admit that the GenII had a much harder time staying above the SOC threshold in this particular location and in the winter the ICE would fire because I'd lose too much engine heat. The GenIII has no problems with SOC and with a grille block the engine temp isn't an issue either.

Besides, few people have a commute like mine.

 

Justin, perhaps I remember incorrectly what warp-stealth is. Do you force battery flow to the wheels ?

 

Yes but according to KenfromJapan it is an insignificant amount. This assumes you are pretending to glide and the energy flow in the HSI is just barely visible.

Hobbit covered it well here.
http://techno-fandom.org/~hobbit/cars/warpstealth.html

 

Well, insignificant unless you have a super long hill like mine. LOL

 

Ah, my error then. I thought you were using battery energy to keep your speed.

 

Ohh dear god no. You take me for an uncultured heathen?