Better MPG on rolling hills than in the flats?

As long as you can keep the hp on the way up at 20, and the coast down is not much over 1,000 feet drop and not too steep, you can do better with hill than on the flat with the Prius, Not so with other hybrids in my experience.

 

You can of course choose not to monitor these parameters for very valid reasons such as very long distance driving, or lack of SG II, or better, monitors of ICE function. I'm not invalidating your experience or the experience of those who have posted agreeing with you because our conditions are all different.

However, when achieving optimal operation of the ICE, by monitoring its efficiency, and when at speeds equal to or higher than 42 MPH, which is what the OP discussed, there is no doubt that the Prius is better on flat terrains.

If there is still misunderstanding regarding this conclusion as a general rule I urge you to search this forum and cleanMPG.com for the threads describing 70 mpg results over long stretches of terrain that is always flat.

There is a debate if super highway mode is better than Hobbit's recently described high-speed mode, but there has been no debate from anyone with significant highway speed experience that I have seen who has argued that hills are better.

If you have high mpg numbers for hills vs flats, or if you have seen threads in which people have used their data and detailed experience to argue that Prius performs better in hilly terrain when used optimally please post the relevant details, many of us are interested.

So far this thread has lacked any data to support the observation that the Prius operates better in hills vs flat terrains, but rather a collection of the impressions of Prius drivers who do not appear to monitor ICE efficiency and are satisfied with the Prius's performance on hilly terrains.

 

Can you point out where anyone with significant highway speed experience has argued that flats are better? My re-reading of Hobbit's description, hills are included. He doesn't claim that either hilly or flat is better.

 

- No misunderstanding.
- No claims that it's true for other speeds or other driving conditions.
- My simple claim is that at low speed, gentle hills provide the best opportunity for pulse and glide so that's where I get my best fuel economy.

Oh BTW. At higher speeds yes I do get slightly better MPG on flat terrain. Better compared with what I'd get at the same speed with hills. But not better compared with what I get at low speed with gentle hills. That's still where I get my very best MPG.

 

Agreed. I call it 'modified pulse and glide' (MPG) on rolling hills, with the Prius in Hybrid-Gravity-Electric mode.

 

1) The OP clearly frames this thread for highway speeds by saying he limits himself to 60 mph. 2) My response to the OP clearly refers to highway speeds and ICE operation exclusively. 3) You chose to isolate one sentence from my writings and claim that you have doubt about my post. 4) I'm glad that the misunderstanding is over, you claim that hills are better for P&G under 41 mph, while I am talking about highway speeds. I have little experience on P&G with regards to hilly vs flats, most of my miles are highway miles. Again the OP was talking about highway speeds not conditions with the ICE not spinning.

Not phrasing this to be confrontational, but we need to be clear so that new Prius drivers do not misunderstand what's been talked about.

 

I agree Hobbit's proposals show no comparison between flats and hills. The reason he mentions hills is to show that the ICE can still be efficient at "high" RPM. His proposed method is more practical than SHM and gets you to your destination faster without causing traffic problems.

However, the question posed by the OP was open-ended regarding rolling hills vs flats at around 60 mph. So I take this discussion to be about which is the ideal terrain for getting highest efficiency from the Prius ICE.

My own experience aside, which from what I gather is the same as that of Mikewhithaprius, evidence first comes from this thread which is littered with a number of people referencing flat terrain mpg at these speeds

New Prius - "Super Highway Mode" Technique (SHM). - CleanMPG Forums

Here are some excerpts

That has also been my experience, on a flat terrain at 55 mph you get about 75 iMPG reading from SG and teh MFD.

In the same thread CleanMPG Forums - View Single Post - New Prius - "Super Highway Mode" Technique (SHM).

If you read his entire post it is clear that SHM gives better mileage on flat terrain than WS on hills, which what I have also found. Again this just answer what the ideal terrain for the Prius ICE is, not for your or my conditions.

Most people who have tried SHM in these threads, search for Wayne Gerdes or JimboK, will tell you that SHM is the most efficient technique to use, yielding over 70 mpg in flat terrains. Wayne actually demos these techniques to anyone who will listen and then some

"Hypermiling" To Much Better Mileage - The Early Show - CBS News

Oh and one from the other thread about tire inflation

There are no claims that I have seen that WS leads to anything higher than low to mid 60s.

Again this does not relate to your or my route, I actually use a mixture of WS/SHM because it is dictated by my terrain and traffic. And most people's terrain and traffic will dictate a mixture of these.

In case my experience means something to you, I got about 60 mpg using Hobbit's technique exclusively on the highway and it is what I mostly use. However, for the few miles that I can hold IGN to 14 at 55 mph I see mpg in the 70s and my SOC near 64%.

 

How about Ultra Highway Mode or Uber Highway Mode, or Super Freeway Mode, since Freeway > Highway

Anyways, looks like a good read, I'll check it out sooner or later.

 

I know, there are so many terms, and then more new terms floating around, maybe we're the ones creating the impression the Prius is hard to drive

Did you catch how the French translated "warp stealth"?

http://priuschat.com/forums/gen-ii-prius-main-forum/91641-why-french-prii-bent-out-shape.html

 

Well, when I "invented"/"discovered" Pulse & SHM (alternating between the two), I wanted to call it Pulse & Slide

OK I didn't invent it, but I discovered it on my own before researching it more.

 

So I actually measured this myself today and my results for speeds around 54 mph surprised me yielding 72.2 mpg. This is not particularly inferior to the SHM numbers published by hypermilers on flat terrains.

For details see the thread below

http://priuschat.com/forums/gen-ii-...ds-72-2-sg-mpg-over-30-miles.html#post1330650