Pulse and Glide technique

[Recumpence]

Hello All,

 

I have been doing some experimentation with Pulse and Glide on my Max. For those who are unfamiliar with this, it is basically just accellerating and coasting. Guys with stick shift cars have been doing this for decades. Prius owners swear by it. However, the C-Max is a bit different in its behavior, making Pulse and Glide a different animal to tame than in a Prius.

 

Here is what I have figured out. I am sure this technique can be refined. But, this will give you a base line to start with........

 

What I do is accellerate to around 5mph over the limit (you can stop accellerating at any speed if you desire). I accellerate typically in Empower mode with the engine power bar at the second line. This gives enough accelleration to keep the cars behind you happy, while not overdoing it. Once up to my desired speed, I let off so the engine shuts off. Then I apply a tiny amount of throttle, just enough to see the tiniest blue bar. This assures that I am not dragging against the engine regenerating into the battery. It allows the greatest coasting distance. So, the car is coasting, with a tiny bit of electric propulsion thrown in the mix. This method has yeilded the best mileage I have ever had. As a side note, I have only refined this technique today. So, all of my previous posts about mileage have been made with normal modest driving, not Pulse and Glide........

 

Anyway, my results are roughly 8 to 12 mpg increase in mileage depending on the terrain, temperature, and speed. Here are some things to remember when doing this;

 

#1 The higher the speed, the less affect Pulse and Glide with give. The reason for this is, the aero drag will slow the car too repidly to gain any appreciable mileage. The sweet spot seems to be around 30 to 40mph. Above 45mph, the Pulse and Glide will gain you very little.

 

#2 The longer you glide the better the affect. Example, lets say you accellerate up to 40mph, then glide all the way down to 20mph, then you Pulse back up to 40mph and repeat the cycle. This will gain you more MPG than pulsing to 40mph, gliding down to 35mph and pulsing back up. I am not sure the reason for this. But, it does make a difference (quite a difference).

 

#3 The proper amount of accelleration is key. The sweet spot seems to be the second bar on the left side of the gauge in Empower mode. If you accellerate more slowly, you will run the engine too long and reduce the MPG. If you accellerate too quickly, you will burn more gas for that short accelleration time, and you may skip out of charge mode and use the battery to help the accelleration. This may seem like a good thing, but I have found optimum MPG accellerating right at the second bar. On my Scan Gauge, this is roughly 40 to 45 horsepower of accellerating and battery charging at the same time.

 

#4 Be careful not to get too carried away with this. It is easy to take you eyes off the road for too long a period. Taking your eyes off the road is obviously dangerous.

 

#5 Experiment with how much electric propulsion to throw in during the "Glide" phaze. You may find that a bit more electric assist during glide, or less will gain you more MPG. Just have fun and see what works best for you.

 

One of the major benefits of this technique (beyond the increase in MPG) is the fact that, at least in my testing, the battery stays charged at a much higher average state of charge than any other method of high mileage driving I have found.

 

This morning, I went for a drive in 41 degree windy, drizzling weather. Normally, my best MPG is around 42 mpg if I really try HARD in weather like that. However, I averaged 57.4mpg! This was at an average speed of 30mph starting and ending at the same location (therefore there was no decrease in elevation to account for the high MPG). Also, my drive ended with more battery charge than it started with! As the day wore on, our weather went down into the 30s with heavy thunderstorms, massive winds, and local flooding on the streets. However, I am still up at 44.5mpg using Pulse and Glide. This is awesome! The last time I tried driving in such horrible weather netted me mileage in the high 30s (around 38mpg). Now, the better the weather, the greater the affect would be. But, I found it encouraging that this works even in bad weather.

 

I must say, I am thrilled with this. It really does not take much effort to get this technique figured out. It does take some concentration at first. But, I have gotten used to it very quickly. If I need to pay closer attention to the road, I just drive normally. But, when I have the presence of mind to focus a bit, I kick in the Pulse and Glide and watch my MPG skyrocket.

 

Oh, one other major affect of this is, you will notice the % of time the engine runs versus electric running will change drastically. My lifetime average shows my engine runs 47% of the time. However, with Pulse and Glide, that number is 35%! And, remember, I have been doing this in inclement weather. In sunny weather, at a 30 to 40mph average speed, I bet you could achieve 25% engine running average.

 

I want you guys and gals to try this and let me know how it works for you.   :)

 

Matt

[fotomoto]

Yes this is pulse and gliding. Not feathering back in any throttle is pulse and coasting.

 

I agree that the second power bar is optimum.

 

On a cold engine, I find its best to pulse the first time long enough to get the ICE up to temp. FE will dip initially but the battery will get full or nearly there and subsequent pulses will be more efficient.

 

Once you get the hang of it, P&G becomes second nature and you'll catch yourself doing it subconsciously.

[SnowStorm]

Matt - a very nice discussion.  I can't offer experience (car not delivered yet) but I do have some questions/comments (same point #s that you used).

1.   So if you P&G around 50 mph, say 45 to 55, it won't be any better than using CC at 50 mph?  We travel quite a lot on nearly level roads with 55 limit.  Averaging 35 or 40 would take too long.
2. This makes sense, your average speed is less and the whole charge/discharge cycle may be more efficient.  Gasoline engines are not very efficient at light loads so when it does run it needs to work fairly hard.
3. Sure wish we had the graph for the gasoline engine that shows efficiency versus load and RPM.  You could fine tune things with that info.

Less engine run % makes sense too.  All the energy must come from the engine so a low % value means it is working harder when it does run - pushing operation up into the more efficient region.  Can't wait to try it all out!

[Jus-A-CMax]

NOTE: Move thread to Hybrid Driving Tips & Techique section since its more revelent here.  :)

[F8L]

Great post!

 

Is there a CMAX engine BSFC map floating around the web yet? This would be very helpful in determining your target acceleration RPM.

 

While not directly applicable to the CMAX, I will briefly detail my P&G method for the GenIII Prius because it is instructive despite the difference in vehicle.

 

My pulse ends at 45mph and my target RPM for the pulse portion is 1,500-1,800rpm. Once I hit 45mph, I lift off the throttle then reapply just enough pressure to cancel regen yet use very little HV battery power. I continue to glide until my speed reaches 25mph at which point I pulse back up to 45mph. Then the process begins again. I've practiced this method with slight variations for over 6hrs one day. I was rewarded with a total trip of 233 miles and 95mpg. Don't ask why I was doing it. A month or so later I went back out for more testing and 2hrs and 62miles later I had nailed 109mpg.

 

I used the accumulated knowledge from professional hypermilers like Wayne Gerdes and bestmapman at CleanMPG.com as well as folks at Priuschat. The BSFC map was invaluable as it saves a lot of testing time while trying to find the sweet spot.

 

The OP laid everything out nicely. I think further refinements could come in the form of mph limits and RPM/load sweet spots. Also a disclaimer about not using P&G in heavy traffic or at high speeds. LOL

[jmckinley]

I think I'd rather ride a bicycle than go through the agony of 45-25-45-25 for six hours.

 

I've done 200 miles in 12 hours on a bicycle and didn't use any gasoline at all. I'm sure it was less tiresome than P&G for 12 hours.  Probably less dangerous too.

[Jus-A-CMax]

Nah...too much hard work. I'll drive to The Mill and take it EV all the way down just past Sherwin Grade (after bypassing 10 CHP and their lasers)....that ought to do it...and not a drop of sweat  ;)

 

ps it was not quite 109 but a good 70+ and thats a fair stretch of road as well...

Edited April 18, 2013 by Jus-A-CMax

[Recumpence]

I have to say a few things here;

 

First, to John,

 

I hear you. Actually, I am an avid bicyclist. I ride a few thousand miles each summer (I live in Northern Illinois). I also manufacture extremely high-end electric bicycles and conversion systems. I am completely in agreement about bicycles. However, it is also obvious from other threads you are frustrated with your C-Max mileage. It is also obvious you are determined to drive it hard. That is fine as well. Every day I have my streak of hard driving. Normally it is related to being cut off or some other such nonsense. I get annoyed and get on it to get around the guy who is driving like a fool. That being said, however, the vast majority of people who buy hybrids understand their capabilities and drawbacks. As I said in another thread, "The right tool for the chosen job".

 

Now, I also feel that you can drive this car casually without doing anything related to Hyper-Miling and still get mid 40s mpg. However this is IN TOWN, not on the expressway. The 45 to 48mpg is found between 25mph and 50mph. Above 50, the mileage drops. That is just the way it is.

 

Now, back to the P&G, I can say that I have alot of fun trying for high numbers on occasion. This is not the way I drive the majority of the time. Most of the time I am using the Bluetooth on the phone with clients for my appliance repair business, or just relaxing between service calls. However, I do find it entertaining to try for higher MPG numbers. This started with my 2002 Caravan (4 cyclinder). I bought a Scangauge and found my mileage went up from 18.5-20mpg up to 23-25mpg by simply paying attention to the efficient points of accelleration and maximizing coasting (also only hitting the AC on coast down cycles). This proved to be a fun diversion from an otherwise boring long day on the road. So, when I bough my C-Max, it was an obvious move to install the Scangauge on the Max and see what was possible. My last tank was 46mpg for the entire 601 miles. This is getting more and more insteresting! In fact, this tank is on track to top 700 miles (though I doubt I will actually get anywhere near that due to the weather we are having).

 

One other thing, I truely enjoy technology and seeing what is capable with a given system. So, I always tend to analyze the products I buy. So, when I spend $30k on a car, I want to know what it is capable of. I know what the car is capable of from an accelleration standpoint, but I want to see how many MPG I can get out of it. That is not as easy to figure out.

 

Lastly, I am a unique driver in one main area, I did not buy this car for any political reason. I have no agenda to push and I am in no way trying to convert anyone to Hybrids or EVs. I just got tired of spending $30 per day in gas. This car costs me $13 per day in gas. The gas savings pays for over half of my car payment per month. So, I am driving a $30,000 car for the cost of a $13,000 car. That is a pretty good deal.

 

Now, back on topic.  :)

 

Matt

Edited April 18, 2013 by Recumpence

[fotomoto]

Great post!

 

Is there a CMAX engine BSFC map floating around the web yet? This would be very helpful in determining your target acceleration RPM.

 

 

 

I swear I've seen one but don't recall where.  I'm thinking Bob Wilson showed one but you know that guy, he's all about charts and graphs, so it could have been something else.  LOL   :drool:

[F8L]

Nah...too much hard work. I'll drive to The Mill and take it EV all the way down just past Sherwin Grade (after bypassing 10 CHP and their lasers)....that ought to do it...and not a drop of sweat  ;)

 

ps it was not quite 109 but a good 70+ and thats a fair stretch of road as well...

Downhill doesn't count. :p

[F8L]

I swear I've seen one but don't recall where.  I'm thinking Bob Wilson showed one but you know that guy, he's all about charts and graphs, so it could have been something else.  LOL   :drool:

I've seen the Prius ones for both 1.5L and 1.8L but not one for the CMAX. :( Bob will find it. I'll PM him. lol

[JohnnOhio]

I pulse and glide a little different. I accelerate to the speed limit  say 35. Then I let off and allow the EV mode to kick in. Then I use just enough EV power to maintain my speed. I average 47+ mpg.

[wamba2000]

Matt, thanks for the insights.  I have found the second mark on the Empower gauge for ICE level seems to be a sweet spot for not annoying other drivers, while maintaining a slightly better fuel consumption level.  On typical city based trips, I attempt to get about 5mph over, then back off enough to let the ICE level drop to the bottom of the gauge, then feather the accelerator enough for the EV mode to kick in.  If traffic is not congested, I will use the EcoCrusie for straight streches, but with my hand on the cancel tab.

 

As others have stated, it is important to watch for traffic lights ahead, when you see a change, back off to coast up to the light and engage brakes lightly for regen power.  It is an adjustment, but gets some added power and helps mileage.

 

My Lifetime mpg is up to 42.6......I remember a couple months ago when it was cooler and running at 34 mpg and I thought it would never go up....and it is still increasing, but at a slower level.

 

Good luck to all on achieving the best performance and lowest fuel costs.

[F8L]

One of the key points about pulse & glide is how it can be used to boost overal average FE. I don't think anyone is saying you should go out and pull a marathon P&G session. Instead, focus on the techniques used and use them when appropriate and when you feel like it. I.e. toss in a few pulse & glide cycles when traveling through residential areas or long boulevards (with little traffic) with stop signs.

 

Most people traveling through a residential area (35mph speed limit) will pull away from a stop sign rather quickly and get up to cruise speed and just stay on the throttle until they reach the next stop sign at which point the brake hard. This is extremely inefficient.

 

Instead, pull away from the stop while maintaining the RPM or power display sweet spot. Get up to speed then glide to the next stop or if the next stop is quite a distance then P&G your way there. Do this once or twice a day and your overall tank average will climb. Evtually it becomes second nature. This is how you trounce the EPA rating without turning into a full on hypermiling menace to society. :p Same goes for freeway offramps. If no one is directly behind you then lift off the throttle and glide to the exit.

[Jus-A-CMax]

Downhill doesn't count. :p

Not all downhill. Airport to the CalTrans yard before Crowley. Past Crowley up to Tom's Place are a bunch of up and down till you reach the lookout of Sherwin grade and then it's truly downhill. Last time I tried this, it was way over 100+ before the airport and then it slowly sucked the MPGs out. By the time I clocked the mpg just past down Sherwin, it dropped like 70 something. So no, not truly all contiguous downhill but it was fun though...better in a hybrid than a gas guzzler  :)

 

By the way, whats a BSFC chart?

Edited April 18, 2013 by Jus-A-CMax

[F8L]

Not all downhill. Airport to the CalTrans yard before Crowley. Past Crowley up to Tom's Place are a bunch of up and down till you reach the lookout of Sherwin grade and then it's truly downhill. Last time I tried this, it was way over 100+ before the airport and then it slowly sucked the MPGs out. By the time I clocked the mpg just past down Sherwin, it dropped like 70 something. So no, not truly all contiguous downhill but it was fun though...better in a hybrid than a gas guzzler  :)

 

By the way, whats a BSFC chart?

Brake Specific Fuel Consumption chart. It shows the efficiency profile of a particular engine. http://en.wikipedia.org/wiki/Brake_specific_fuel_consumption

 

Here is an example for the Prius GenIII

[Jus-A-CMax]

Brake Specific Fuel Consumption chart. It shows the efficiency profile of a particular engine. http://en.wikipedia.org/wiki/Brake_specific_fuel_consumption

 

Here is an example for the Prius GenIII

Thanks, not making a whole lot of sense to me right now but I'll look into it further. How does one get to plotting out such a chart, scangauge?

[F8L]

Thanks, not making a whole lot of sense to me right now but I'll look into it further. How does one get to plotting out such a chart, scangauge?

Nah, they are usually put out by the manufacturer. The engineers come up with this stuff while desiging the engine. Then they test it on an engine dyno and output a map. In essence anyway. lol

[SnowStorm]

Would like to see the C-Max chart on the back of a T shirt!

 

A big point of these charts is that a gasoline engine must be driven to high load (torque) output to be efficient (but not to high speed).  If engines had equal efficiency at all load/speed combinations, I don't think there would be any point in using P&G or, for that matter, in building a hybrid at all!