Pulse and glide at higher speeds (66 ~ 68MPH) beats super highway mode at lower speeds (50 ~ 55MPH)?

Re: Pulse and glide at higher speeds (66 ~ 68MPH) beats super highway mode at lower speeds (50 ~ 55M

You will have arrows above 41 mph.

 

Re: Pulse and glide at higher speeds (66 ~ 68MPH) beats super highway mode at lower speeds (50 ~ 55M

Nice mpgs at that speed, Rich.

Above 42 mph or so there is not a no-arrows state (sometimes when car is warming up or down big hill, but not really an official "thing"). At higher speeds the closest thing you have is warp stealth ("stealth", by the way, is defined as EV use on the Prius...no arrows would be considered a "glide", even though a little secret energy comes from the battery in that case), where you'll see yellow arrows from the battery to the wheels. That's a no-gas mode.

 

Re: Pulse and glide at higher speeds (66 ~ 68MPH) beats super highway mode at lower speeds (50 ~ 55M

There is a rare spot at about 0.6 BTA, but like you say it is practically useless

 

Re: Pulse and glide at higher speeds (66 ~ 68MPH) beats super highway mode at lower speeds (50 ~ 55M

This might be of interest (mostly to ystasino )

245 mile trip at 65.7 mpg Scangauge (would be 67.8 on MFD - from calculating from previous mileage on MFD before this drive) through Vermont and hilly parts of Mass. The route covered all sorts of driving from 25 mph pulse and glide areas to 55 mph and heavy accelerations. I did use warp stealth when it would not lose any momentum, but for the most part when in the 50-55 mph areas I used SHM as much as possible. Was up at 60 mph sometimes. I really liked locking into IGN 13/14 TPS 17/18 or thereabouts, gaining speed downhill, losing it uphill (driving with load), so more terrain was covered at a very high instant mpg in many cases.

In these faster parts, speed variations were not huge on my part. Mostly kept momentum and just drove with a gentle foot, nothing too tricky. Got to feel a few 3000 RPM hills!

Mike with a Prius: Drive through the mountains to Vermont

 

Re: Pulse and glide at higher speeds (66 ~ 68MPH) beats super highway mode at lower speeds (50 ~ 55M

Interesting, why are you using IGN rather than kW? It's funny that you ended up using the SHM metrics while I end up using Hobbit's kW xgauge.

Nothing too interesting in the current tank as all of my trips are what I have already published. The last 10 days I haven't left the city and my mileage in this tank and in high temps has dropped to 59.3. Hoping to improve my mpg to over 60 using this weekend's trip to DC...

 

Re: Pulse and glide at higher speeds (66 ~ 68MPH) beats super highway mode at lower speeds (50 ~ 55M

Cause after someone asked me (here or elsewhere, I forget), I looked at RPM related to kW and found a very nice, predictable relationship (1650RPM=15kW-ish). So I can watch RPM, which updates almost instantly compared to the slow kW reading, and know when I'm in the sweet spot with that. That way I get RPM, secondarily approximate kW, plus IGN and TPS, and another of my choosing (SOC, occasionally BTA). Five X-gauges on a Scangauge, it's revolutionary haha

 

Re: Pulse and glide at higher speeds (66 ~ 68MPH) beats super highway mode at lower speeds (50 ~ 55M

I have iMPG, SOC, BTA and kW. Watching BTA is my favorite these days

 

Re: Pulse and glide at higher speeds (66 ~ 68MPH) beats super highway mode at lower speeds (50 ~ 55M

Maybe joining the party a bit late here, but I have two observations on this topic. The first one is about efficiency. Logic would dictate that utilizing the ICE in it's most efficient state (15kw~) would produce the best MPG performance and sure this is true-for the most part. But, just because the engine is running at peak efficiency (fuel burned vs power output) does not mean you will achieve the best MPG. MPG is calculated via speed in MPH vs fuel burned. If you are doing 20 mph at the best possible ICE efficiency, it does not mean you will achieve better MPG over say doing 50mph at a worse engine efficiency. To reiterate, this would be due to the relationship of fuel burned to speed. Hobbit's theory involves running at high ICE efficiencies at high speeds. We all know that at high speeds, wind resistant is killer. Wind resistance is NOT linear. The resistance at 70mph is more than DOUBLE the wind resistance at 50mph. So, my point here is that efficiency-although it is important-is not direcetly related to overall fuel efficiency. Instead of the thinking: "Try and maintain peak ICE efficiency", the proper method would be to try and maintain peak speed to fuel consumption ratio's, and to do this will often require NOT running at peak ICE efficiency. An example I could give you is this: Is it better to accelerate at peak ICE efficiency going uphill, thus SLOWLY reaching your target speed, or is it maybe better to step on it a bit and utilize 20% more fuel whilst reaching your target speed in half the time? Obviously it would be better to accelerate at less-than-peak RPM's if it means in the end you have expended less fuel.

My second observation is in regards to terrain as it applies to this theory. Hobbit utilizes this method on hilly terrain, thus allowing him the benefit of downhill regen and better stealth mode. On flat terrain, this style of driving is FAR less efficienct because their are no downhills to generate "free" power. The highways in CT are generally very hilly, and their are amply opportunities to utilize regen and stealth mode. If I were to do this style of driving on Long Island, it would do nothing but hurt my mileage, because there are no hills on the Expressway that allow you to utilize extended high speed stealth...All that would occur is a loss of speed that you have to make up by revving the engine....Alot of people do not realize that the Prius is not much different than a regular car. The MAIN difference is that the Prius wastes far less energy. It is (unlike a traditional vehicle) capable of harnessing what would otherwise be wasted energy during deceleration. In another words, it has the capability of storing energy that it has created, and using it at a later time. In a regular car, when you brake, all of that kinetic energy is wasted as heat on the brake rotors. All of the gas being burned at a light is wasted in the form of exhaust heat. In the prius, this gas used at a light can be stored in a battery and used later on. And instead of wasting its decleration power, it stores it again in the battery and can be used later on.

So, when you live in an area with many hills, vs an area with NO hills, you essentially never have a circumstance where energy could potentially be converted from one form to another.

I hope that more Prius owners will try and understand and better utilize the principle that best MPG is not a matter of the efficiency of your fuel consumption but rather, it is a relationship between fuel consumed vs speed and also, it is about HOW EFFECTIVELY you can capture energy that would otherwise be wasted (i.e. the perfect amount of braking to capture as much energy as possible, or, when to use stealth mode vs. regen, or when to accelerate with or without the ICE) All of these play a major factor in overall fuel mileage, and I think they are often overlooked and not undertstood, which is why we see so many Prius owners getting far different MPG's at the end of the day.

After all, on every trip, there is only ONE "best" way to drive it to achieve best mileage. It is not a matter of "is Hobbits method better than PG at low speeds" it is a matter of "On this trip, with these conditions, which one is better to use" No one method is better than another. But knowing which one to use and when is the key to success.

 

Re: Pulse and glide at higher speeds (66 ~ 68MPH) beats super highway mode at lower speeds (50 ~ 55M

There are other circumstances too. Like when you are on a single lane country road in hilly country stuck behind a slow car, I think you get into a circumstance I describe as the backside of the power curve (no obvious pun intended). You cant accelerate out so you waste a lot of fuel as the engine power dominates power delivery, and you cant glide down hills either because by now you have a stack of traffic behind you. To make matters worse you might even have to brake downhill !

 

Re: Pulse and glide at higher speeds (66 ~ 68MPH) beats super highway mode at lower speeds (50 ~ 55M

At least braking down hill will store some momentum energy ;-)

 

Re: Pulse and glide at higher speeds (66 ~ 68MPH) beats super highway mode at lower speeds (50 ~ 55M

The glass is half full . . . or the glass is half empty. Are you 'stuck' behind a slow car? or do you benefit from being behind a slow car? No one's gona hate your guts for driving slow, when they can see it's the car or truck in front of you that's setting the pace. I find it to be a wonderful thing ... when a big ol grocery truck is in front of me ... lopping along at a wonderful 45 -50 mph. He's cutting my wind resistance a bit ... so - why on earth would I want to be the pace car? Yes - as stated above, the ICE may be more efficient at less efficient speeds, so the bare fact will not necessarily get you into record setting tank full ranges, imo. But ... I may be wrong ... I'm no guru ... but a half dozen years never let me get ranges like the one below, while doing 60mpg:


I'm just say'n . . .

.

 

Re: Pulse and glide at higher speeds (66 ~ 68MPH) beats super highway mode at lower speeds (50 ~ 55M

thats fine if the road is flat, but out here I live in a band of pretty hilly country.

Given that, a car doing a constant speed in front of you doesnt allow you to glide down a hill giving the car its head and making the best of the speed to get up the next hill. In that situation you are braking to restrain the car going down hill, and consuming fuel pretty heavily going up.

As someone else points out you do recover some energy braking, but the efficiency of that recovery, and the efficiency of the system to deliver that power into motive force, again works against maximising the potentials.

 

Re: Pulse and glide at higher speeds (66 ~ 68MPH) beats super highway mode at lower speeds (50 ~ 55M

All true. There ARE additional dynamics of down hill driving. Already, I mentioned going up hill, you have less wind drag behind a truck, AND the additional benefit of going slow. Driving down hill means less wind drag too. Thus, your regen is greater going down hill because you're braking harder. Our two homes in different states both have hilly areas surrounding us - and we still maintain great efficiency, because we find we can make slow trucks work for us as a pace vehicle ... so much so, that I find it a bummer when there's no truck around to leach off. So, yea .. we get high mpg's on flat ground as well as hilly ground.

 

Re: Pulse and glide at higher speeds (66 ~ 68MPH) beats super highway mode at lower speeds (50 ~ 55M

This is fairly easy to understand. It is classical mechanics at best. The car have good aerodynamic in unidirectional, like human bipedal...not good at swaying. I found it to be good to accelerated when driving straight and brake when turn or sway. The unnecessary heat generated from friction when turning the tires as well as the side aerodynamic drag could impact your mpg?
You just have to study your routine route and noted when is best to accel or deaccel/brake. Some idiots always think they are right and not listen to the highway engineers/or the speed limit.