Real World MPG for our 2010 Prius. After 2,173.9

I mean no offense to some of the other folks who've provided earlier answers to the inquiry about a definition for pulse-and-glide, but Bob's succinct answer provides the guts of the response about what it is. How to do it is another story.

Pulse-and-glide really is not a valuable tool on the highway, and the return is difficult to find. In around-town driving, though, P&G is a fabulous tool for fuel economy.

I would suggest you keep these things in mind:

1. Momentum is the key; allow the car's weight to help you maintain current velocity.
2. Use brakes sparingly.
3. Learn how to truly "glide" in your car -- no acceleration, no braking, no coasting. The glide is that state when no power is applied to drive the car and no regeneration is occuring.
4. An even acceleration is best; try to achieve the target speed sooner, rather than later, but it can be done efficiently. Using the HSI Screen (Hybrid System Indicator), you should be able to accelerate to speed and still keep the "Eco" light on. (I'm usually pushing this so that the indicator is between 3/4 and 7/8 to the right and pretty close to the "Power" area.)
5. Don't just follow traffic patterns, but anticipate them and check far ahead to see if traffic is slowed or stopped or if there is a red light ahead. Most people waste huge amounts of gasoline by actually accelerating into red lights!

Bob's concise definition got close to the OP's request to get everything in twelve words. I'm hoping the above will provide a bit more additional assistance.

 

First I want to thank you for posting the speeds as well as the MPG numbers. Too often we get just MPG without the speeds and that can be terribly misleading.

Is this table accurate for your vehicle?

	Column 1	Column 2	Column 3	Column 4	Column 5	Column 6
0	min mph	max mph	avg mph	MPG	model	comment
1	55	55	55	55	NHW20	at 65 mph?
2	55	70	62	60	NHW20	Ok

.
The reason I ask is your vehicle performance seems a little different from results from other Prius. What I've found with my NHW11 and a report from an NHW20 owner and my wife's ZVW30:

	Column 1	Column 2	Column 3	Column 4	Column 5
0	min mph	max mph	avg mph	MPG	model
1	60	60	60	52	NHW11
2	65	65	65	52	NHW11
3	60	60	60	57	NHW20
4	65	65	65	53	NHW20
5	60	60	60	57	ZVW30
6	65	65	65	51	ZVW30

.
Source data for NHW20 and NHW11:


Source data for ZVW30:


What I found with my NHW11, a 2003 Prius, there was no significant change in MPG out to 65 mph. But once it exceeds 65 mph, the mileage falls off significantly. In contrast, the NHW20 user report and my wife's ZVW30 don't have a similar MPG plateau or fall off. They follow the expected aerodynamic drag curve.

Your data at 55 mph has me really scratching my head. It suggests that there may be a slight dip or at least a flattening of NHW20 performance under 60 mph. This plateau is evident in my NHW11 data. It would be interesting if you could try a run at 65 mph in your NHW20 or better still, at 62 mph to do a head-to-head comparison with your 55-70 PnG. This would quantify the PnG improvement.

Thanks,
Bob Wilson

 

Great posts yet again by A64 and Bob!

I think it's a learning curve, watching the HSI as stated and the road ahead to anticipate. A perfect example, (So I know the car is capable) I drove a 11.9 mile trek yesterday after getting gas (reset Trip Meter) and this route has several traffic lights. I never got into the power range with accelerating, and anticipated the road ahead and the traffic lights. I was able to achieve 61.7 MPG on the route, be it only 11.9 Miles, but it's doable.

I see some posts where "I am not getting the best mileage and I am travelling at 75MPH" I don't think those are ideal conditions and your mileage tends to "suffer" a little in that case.

But if you mindful you will be able to get those high number that help round out when you are not able to given the road conditions and traffic etc.

Just thought I would share my experiences as well.

 

it would seem that the traffic tickets one would accumulate in a year of driving pulse and glide would offset the fuel savings. Am I wrong?

 

Is your route hilly? My area has a lot of hills and it also has a lot of lights, so it seems I am constantly having to start from a stop on a uphill slope. I try very hard (and have had a Gen II so am aware of P&G etc.) but only manage to achieve around 45mpg. If this applies to you, see http://priuschat.com/forums/gen-iii...est-difference.html?highlight=uphill+downhill. Also, how long are your daily commutes? If they are short (like mine), the car will not be operating at full efficiency.

 

I don't commute. I office at home. so I drive to do things with friends, to go shopping, to run errands. when I have a photography job or go mountain biking, I still take my old Land Cruiser which gets 14 on the highway, 10 around town!

 

HI bob,

I need to get some disclaimers out of the way before I write anything else.

First and foremost: my Prius is a rebuilt salvage vehicle. It looks like a duck, talks like a duck, but it may happen to be different from a normal vehicle in some way that I am not aware of.

All of my numbers are by no means, a scientific recording of data. They are just based on my loose memories and what I can remember and apply to every car journey. The numbers are probably therefore at least 10% off, but as I don't write it down, I could not tell you exactly what happened.

The 55mpg quote is from when I made a trip to Lewisville (Dallas area). 280 mile trip, and except for maybe 30 miles exiting Houston and 30 miles entering Dallas, I had the cruise control set to 55mph for the whole way. I achieved 55.5mpg according to the MFD when I got to the destination. I must've had a hundred trucks pass me by, that was kinda embarrassing, but I heard 55mph was the most efficient speed to go at and wanted to see what I got. Arriving after a 300 mile trip with half a tank remaining is a good feeling!

One time, out of necessity, I had to get to a destination about 60 miles away from my current location with just one gallon remaining. So I PnG'd tirelessly until I got home. Luckily the traffic was pretty calm and chill and let me do my thing. I got about 60mpg.

Then another time I PnG'd on the highway home from a friends house 20 miles away just for fun. I achieved 68mpg on that stretch, I actually have a picture of that one on my facebook.

Something like 99% of my driving is in the city, amongst aggressive drivers, or with myself being aggressive. Therefore, my usual fuel economy does not top 40mpg often, so when I get higher than that, I take note! And skip a little, but I digress.

Regarding making some more trips at certain speeds, what do you need exactly, a 62mph trip with PnG or SS (steady state)? I'm willing to do it but it may take a few days to get a good opportunity to go on the highway again.


__

So basically my numbers may be way off, but I have a general idea what gives a good working PnG trip and so I was just advising Lutece of my findings.

 

Excellent! I've read of several others and then there is the legendary AutoBeYours. Did you do this salvage recovery? My only curiosity is how are the tires wearing and the alignment?

That is OK. It means you're not quite as Obsessive Compulsive about it. <GRIN>

No apologies needed! The essence of the scientific method is to test and your data is excellent. In fact, it fills begins to fill a gap that I have no data ... standard NHW20 performance at lower speeds.

Excellent!

No problem, we own these vehicles for years so when you get a chance, it would be interesting to fill-in this last row:

	Column 1	Column 2	Column 3	Column 4	Column 5	Column 6
0	min mph	max mph	avg mph	MPG	model	comment
1	55	55	55	55	NHW20	experiment
2	55	70	62	60	NHW20	PnG test
3	62	62	62	. . .	NHW20	reference

.
This will quantify the PnG versus the equivalent steady speed.

BTW, we're finding our NHW11/NHW20s appear to have a maximum range speed of 18-20 mph. If I were in the desert with the next gas station twinkling in the distance, I'd be holding the speed at ~18 mph and on the shoulder creeping a far as possible with the last of the fumes.

Sharing data is great and adding an equivalent, steady-state speed completes the picture, especially from the same vehicle and driver. Since I grew up in Oklahoma, just keep a weather eye out for the winds. <grins>

Bob Wilson

 

Hi Bob! Prepare for a lot of text here!

I didn't do the recovery myself, I hardly know anything about the mechanics of cars I purchased it from a car dealer who had bought it at auction, after it had been rebuilt.

The alignment is fantastic, I can practically drive without my hands on the steering wheel most of the time! As for the tires, they have been really, really bad. I think. Again, I don't know much about cars, however two of the Integrities developed punctures in the sidewalls after about 15,000 miles of my driving, and the car had 7,000 on it when I bought it, so assume 22,000 miles on the tires. I have since replace them with Falken Sinceras, which are fantastic, and I have a warranty on the Falkens so if they pop, I can get them replaced free. Overall though I don't think the tires did too well.[/quote]

I would like to be though! If I had the technical know how, I would hook up a netbook to the car to record mountains of data on how my fuel economy varies with speed and throttle pressure, maybe even have one of those scientific weather measuring devices attached to the car so I can measure the wind speed, humidity, temperature, etc and see what bearing those things have on fuel economy. They really should have a course in a college somewhere on the physics of fuel economy!

Whats a lower speed by your definition? Has no one tried crusing at 55mph? Serious question! I hope I'm not the only person in the world who actually drives like that

I should note that the examples I gave that merited that were both on the highway, I kind of missed stating that. I just wanted to mention it because I think someone said something about PnG being ineffective on the highway - well, in my experience, it is effective, its just that when you go above 70mph or so, the relative windspeed knocks your overall speed down so fast that it isn't worth it. At lower speeds though, like topping out at 60-65mph, the speed reduces slower and so you can get in more of those 99-99-99 segments.

Ok, so all I have to do to fill out the table is cruise at 62mph? No problem! I think I can do that tonight!

I see what you are saying here, however, and this has a huge influence on my driving: I don't wish to present a hazard to anyone else on the road, and I don't want to give Prius drivers a bad reputation, so even on my last fumes, I will keep up with traffic; however, I WILL PnG mercilessly to achieve the maximum fuel economy. Typically, when I get down to that last pip, I will reset the fuel economy meter so that I can see how I am doing with just that one gallon, and get an estimate on how many miles I have before the "Add Fuel" warning comes on.

That said, how can you get the maximum range at 18mph??? From what I have seen, I can't get into the 40mpg's until I hit 30mph at least. I read somewhere on this forum that 48mph was the best speed for fuel economy, although that is largely impractical on both city and highway roads. When I am going for the max range, I will just let the speed at which I pulse go down by 50-10mph, maybe taking it as low as 25mph before slowly pulsing up again to 40mph.

Well I am happy to help! Just tell me what conditions I need to drive under, I shall have some data for you shortly!!

 

Imagine you have just descended into Death Valley at midnight only to discover the gas tank is almost empty. In the far distance, the other side, you can see the blinking lights of a gas station. The only other traffic are snakes and stinging insects and you don't want to have to walk towards the blinking lights with an empty gas can ...

Without other traffic, run the Prius at 18-20 mph, constant speed, and you will minimize how far you'll have to walk at 5 mph in the blazing sun and Death Valley heat. Now if you see another vehicle, put on the emergency blinkers and roll to a stop. See if they'll help. If not, 18 mph until the last of the gas is gone is your best survival strategy. <cue the "Twilight Zone" music.>

From a number of tests and experiments, we have this graph of the earlier 1.5L, NHW11 performance:

The "gray line" is the expected MPG at any given speed for the NHW11. The NHW20 should have a slightly better line but with a higher peak in the same 18-20 mph region. Notice those "black dots?" Those are the average leg speeds from the famous NHW20 marathon. <GRINS>

Then I've been known to pull a few tricks. For example, here is what I got after 10 miles at 15 mph:


If you really want to see some impressive numbers, try some of the low speeds ... say around a parking lot on a day when there isn't any other traffic. It is boring, so bring some good tunes. <GRINS>

So when you hear the "Twilight Zone" music, you'll know what speed to hold. <GRINS>

As for conditions, side winds of say 15-20 mph are OK. But if you have a head or tail wind, try and estimate the velocity and angle and we can show you how to estimate the effect. For example, straight at you would be the cosine of 0 degrees, 1, times the wind velocity added to the vehicle velocity. At 45 degrees, it would be about the cosine of 45 degrees, .707, of the wind velocity added to the vehicle velocity. For our purposes, this is close enough.

Bob Wilson

 

I think it may have been me that said that I believe that P&G had little effect at "highway speeds" It seems that quite a few consider highway speeds to be speeds above 75MPH or so. I believe if you P&G between 55 to 75 say you will get much better fuel mileage than running a constant 75 because your average speed is lower.
LOOK at Bob's graph. I'm a boogger eating moron compared to him, but I can read charts. Pretty much what they tell me is there is ONE sweet spot, 18 MPH. Above that mileage begins to fall off. A lot of people want to think there is a sweet spot up there at highway speeds, but it just isn't so, or I don't think it's so anyway.
I believe that P&G may be real beneficial at speeds below 46 MPH because unless I'm mistaken below that the ICE may shut down. From what little data I have been able to get it WON'T shut down above 46 MPH. What that tells me is that while P&G may be effective at speeds above 46, it really becomes effective below 46 because of ICE behavior (I'm talking Gen III here) or apparently ZVW30, but while I believe the earlier cars will shutdown the engine above 45 mph, it isn't efficient because you are using electrical power to spin a dead motor.
I believe the most effective thing any of us can do to get better mileage is to slow down if highway driving.
An opinion of mine is that if you really want to get good mileage, get off of the highway and take secondary roads.
If your in a hurry and want to take the highway, set the cruise control and set back and enjoy listening to music or something. An un-educated opinion of course

 

Bob, I read your post, I'm just waiting until I can do a 62mph cruise to further our conversation.

A64: Sometimes you just have to take the highway. Sometimes its more convenient. Sometimes its the only way. I can't take country roads up to Dallas for example, only I-45. I, fortunately, am able to choose what time I leave on a trip though so I tend to leave at midnight, because at that point, the road is mostly empty; usually you will see a truck-trailer every mile or two but thats it.

So basically, I can choose whether to go at a steady 55mph (or higher) or PnG between 55-70.

I guess it just depends what kind of vehicle you had before the Prius. I had a Jeep that would reach 19mpg on the highway, 14mpg otherwise. Compared with that, I could drive the Prius at 106mph and probably still double what I got in the Jeep! Anything above 36mpg and I am good; anything more than that and I am very happy!

I don't know what the 2010 does with regards to shutting off fuel to the engine but I assume its the same, I mean, why not? It saves fuel, and thats the point right?

With regards to using electrical power to power the motor and engine; the engine will generate enough power on the pulse to overcome that, I'm sure. Especially on the highway where you are just constantly driving at efficient speeds. Sometimes it seems to me like highway driving is that efficient that there is an excess of battery power, judging by the green battery icon appearing frequently on long trips, and almost always when I get on the off-ramp.

 

To say that it's "much easier ... to use the handy search box" is rarely-if-ever true. I've tried using the so-called search box MANY times, and have generally been taken to a listing of about 50-or-more POSSIBLE threads that MIGHT help me out, but seem to provide info to TOTALLY unrelated subjects.

Personally, I much prefer the "helpful link provided" within a response to a question as that posed by those of us who may ask for guidance from time-to-time ... rather than a simple "use the search box" reply. If a person doesn't have time to be helpful, he/she shouldn't take the time to respond at all ....

 

No rush on my part. You're helping us to understand this wonderful vehicle and any data points contribute to our knowledge.

THANKS!
Bob Wilson

 

Before responding to this, I don't really get what you are implying "between the lines." Are you assuming that someone driving like this would be exceeding the speed limit during the pulse phases. Are you implying that a cop would pull you over for going to slow. Are you implying that a cop would ticket you for impeding the flow of traffic? What do you mean by this?

When I P&G, I am usually on a 4 lane highway through our small town with a maximum posted speed of either 35 or 45. I can be in the right hand lane and "pulse" up to about 45 (in a 35 zone), and then "glide" down to about 34 or so. I then repeat this over and over to my turn off the divided highway. I glance periodically in my rear view mirror to make sure that I am not holding up traffic. Rarely is this the case, since the speed demons can pass me on the L. Of course, if they pass me toward the end of a "pulse," they really are risking a ticket by our friendly police force!

When I am on a two lane road, I REALLY pay attention to if there is any traffic behind me. Most of the time there is not (its a small town). I think in general that following someone who is P&G'ing can be mildly annoying so I alter my P&G to be less noticable. I accelerate to just shy of 10 over the posted speed and then use more battery in my glide phases to keep the speed up longer (staying below 1/2 way to keep ICE off). I also will accelerate again sooner than letting speed drift down to just below posted speed cause it seems like many people just will not drive at the posted speed limit!

When on hills, I will use the hills to extend glide and/or recharge the battery as necessary depending on the current SOC and knowledge of the route ahead to maximize the MPG. When I know I have a significant hill coming up, I will sometimes use the previous downhill and or more speed to use max momentum to carry me up the hill (to minimize battery). If there are no cars behind me, sometimes I will hit the top of the hill at only 10 mph or so. That is when I feel like I really nailed it! I then use the downhill to assist my next pulse!

My second tank fill up is going to be very close to 700 miles!

 

And we wonder why everyone hates most Prius drivers…

 

I drive my Prius in "PWR" mode always and stay with or slightly exceed traffic speed. I will not impede traffic to play games to obtain higher mpg ratings; IMhO, that is potentially dangerous given how the majority of US drivers don't really know how to drive a car....altho way too many seem to "THINK" they can TEXT and drive!

Despite that, and now cold (20sF) temps; got over 42mpg on a long freeway trip with 3 people in car over last two days. Good enough for me. OTOH, in metro area driving, prior to trip, got a calculated 50mpg, while car showed 48+. DFO

 

I drive mostly highway during the week and I, too, go with the flow and drive around 60 - 70 mph. With two people in the car, I'm averaging around 44 mpg. I just drive the car as I would any other car and I have it on normal mode. The only time I go to power mode is if I'm merging onto the freeway.

 

the difference between my 2 Pri's used to be just under 1½ mpg. that has grown simply because they are driven by two different people with two very different driving needs.

but i am happy with my results. in about a month, the SPM will be gone and the 2010 will be more shared. i expect that mileage to drop a bit, but will be interesting to compare the difference

 

With winter here in the Northwest MPG's are running around 45 MPG's
with my wife driving who does not drive for MPG.

Of course in the summer the average MPG's is high 40's to low 50's.

When I drive its usually at least 3-5 mpg's more than when my wife
drives.

We have over 40,000 miles and have had Michelin Energy Saver
tires for about the last 30,000 miles, 195x65x15, with max pressure
in all 4 tires @ 44psi. Oil is the best you can buy, Mobil One 0 W 20
with 4 quarts in the engine so not to overfill.

Gas is all year long with 10% Ethanol in Oregon, with regular gas and
no Ethanol we would have at least a 3mpg increase.

alfon