After 6k miles on my 2011 Prius -- Observations

Once I drove 75-90 mph in South Dakota/Montana for hundreds of miles and got around 45 MPG. Recently drove in Pennsylvania hilly highways at 70-75 mpg and got 50+ MPG. I don't hypermile. I really don't understand the 30s MPG situation you have, even at high altitudes, unless you are only driving 3 miles at a time. May be something is not right with your car.

 

OP needs to answer some questions such as the ones I posed at http://priuschat.com/forums/gen-iii...s-my-2011-prius-observations.html#post1340283.

However, we might need most of the questions at http://priuschat.com/forums/gen-iii...-answer-these-questions-esp-if-youre-new.html answered to better understand what's going on and whether the mileage he's seeing is normal for his conditions and drives.

 

Top tier gasoline does make a difference in all the cars i have owned always better mileage. Regarding wind yes it effects mileage but not stability to an extent i feel unsafe in my prius. You should drive a box ( scion xb/ Honda element) i did and the prius is much better. The boxes were not scary but you had to pay attention to your lane position in traffic.Mileage in the boxes was terrible especially in winter and they were 4 cylinders.

 

I'm consistently getting 43mpg according to the dash monitor. This is with 87 regular octane. Thus is mostly city driving with list of hills. No matter what I can't improve. Are you using 93 octane for higher mpg?

 

disclosure...

First _ I'd like to say that I bought my Prius
to experiment with hypermiling - that is to
extract the best MPG that one can possible get
so my expectations are different from yours.
After 13K miles on my 2010 Prius,
I am getting between 52mpg to 66 mpg per
a tank with an overall 59 mpg from day one.

A 2010 Honda Insight can be hypermiled to produce
an overall 75 MPG but it requires more driving
skill than a 2010 Prius (which has a top hypermiling
overall 65 mpg). The Prius main advantage is that
it has a larger, more active, and more helpful
community (e.g. Priuschat.com) than the Insight
community. The hypermiling car of choice is the
2000 Honda Insight. The Prius easier to
hypermile but (like a bicycle with training wheels)
it's not likely to deliver top hypermiling performance,
> overall 90 mpg.

I have also observed that my 2010 Prius main fuel
display (MFD) MPG tends to be about 4 mpg too
high. My ScangaugeII because it can be manually
calibrated is only about +/- 1 mpg off for the
most part.... If only I could calibrate my Prius MFD...
With respect to the Prius gas mileage

I'd like to say...

Like a high end BMW - if a Prius is not
driven the way it was designed to be driven
then it will return reduced performance with
respect to its advertised rating. A Prius's fuel
efficiency depend on a variety of factors
that you probably didnot consider before you
purchased it - A Prius fuel efficiency
depends on how much long it is driven on the road,
the outside temperature when you drive it, whether
it is driven in hilly or flat roads, how much cargo
is being carried, what type of gasoline you use, what
kind of weather you drive it in, what tire pressure
you are using/what tires you are using, you
must avoid depending on battery (EV) power
exclusive, and whether you drive it aggressviely.

a more fuller explanation
===========================

1) A FULL HYBRID GAS-ELECTRIC VEHICLE like a Prius
does not achieve its rated fuel efficiency unless
it is driven over 25 minutes(>55F,<40mph) to 40
minutes(>10F,<40mph) per trip/session or over
15 minutes (>30F, driven faster consistantly at
mainly between 50mph to 60mph). This is because
there is an energy cost to warming up the Prius
catalytic converter from a "cold" start. In colder
climates the cost of "cold" start is more severe,
Canadian dealers often install electric engine
block warmers onto Prius that can migitate this.

2) The optimum outside temperature for the best
fuel efficiency for a Prius is between
55 Farenheit degrees to 75 Farenheit degrees.
Grill Blocking can mitigate this loss of power
from cold city driving. When the outside temperature
drops below 30F, the Prius gasoline engine
needs to be run periodically to keep the
catalytic converter warm - it is more fuel
efficient if the driver runs the engine periodically
than if the Prius's main computer automatically
turns on the car just to heat up the catalytic
converter. One can monitoring the Prius
engine's coolant temperature via a ScangaugeII
Xgauge FwT or CwT to determine when the
ICE is getting too cold ( < 120F)

3) if a Prius is driven in a stop-and-go hilly roads
mileage can drop significantly ( this is also
true for conventional vehicles). Fuel efficiency drops
when any vehicle must come to a full stop at the
bottom of a hill and accelerate from a dead stop
from the bottom of the hill. There are hypermiling
techniques to mitigate this type of driving environment
but if I've assessed your abilities this is not a
viable option for you. It is easier to get
better MPGs on a flat road or slightly inclined
road than on steep hilly or mountainous roads.

4) The 2010/2011 Prius fuel efficiency is sensitive
to the weight in the rear of the car. For example,
the Prius gets slightly better fuel efficiency when
the fuel tank only 25% full than if it is 100% full.
(this is only 65 pounds). My current hypothesis
is that the extra weight in the rear of the car
adds additional higher rolling resistance to the
rear tires and that this lower the Prius fuel efficiency.
IIRC a Prius is designed to carry a total passenger+
cargo weight of less than 880 lbs.


5) The Prius Fuel efficiency is better if you can use
100% gasoline instead of E10 or E15 gasoline. Ethanol
based fuels have less energy than regular gasoline so
E10 and E15 tends to give lower FE performance.

6) Every gasoline car gives worst MPGs in the winter
than in the Spring-Summer-Fall. Bad weather - especially
the type of weather that causes traffic jams and slow
traffic reduces fuel efficiency in general. Grill
Blocking can mitigate this loss of power in winter
urban driving environments (its value is questionable in
winter highway driving environments).

7) High rolling resistance will reduce the fuel efficiency
of any vehicle but the Prius fuel efficiency more sensitive
to the tires' rolling resistance than other vehicles with
more power (e.g. BMWs). On the flip side a Prius fuel
efficiency benefits more from overinflating the tire pressures
than most other vehicles because of its aerodynamic design.
Hence, raising the tire pressure from the door specs
(35 psi front/33 psi rear) to its max side wall psi
(44 psi front/42 psi rear) can increase your fuel efficiency
without any significant loss of road traction -- albeit the
ride will be stiffer. An alterative way would be to swap your
OEM tires for Low Rolling Resistant Eco Tires.

8) Draining the Prius Traction battery lower than about
42% (2 bars on the SoC HSI indicator) will cause the
Prius computer to automatically turn on the gasoline
engine to recharge the battery and cause the MPG to
drop. To get the highest MPG possible, a driver must
avoid depending on battery power ( HSI indicator should
be pass the "ECO" middle marker to insure that the
car is depending more on the gas engine OR the HSI
indicator should be in the CHG mode indicating that
the battery is being recharged via the regenerative
brakes). On can monitor the Prius Traction battery
state of charge with a ScangaugeII programmed
Xgauge "SoC."

9) A Prius fuel efficiency depends on the driver NOT driving
it aggressviely. Jack rabbit starts, speeding to a stop,
weaving in an out of lanes, driving over 65 mph will reduce
its fuel efficiency. A Prius gets its best fuel efficiency
when driven over 30 minutes at a constant speed (with no
stopping) somewhere between 20mph to 50 mph. Just adding
more time to your drive/trip so you don't feel the need to
speed can greatly improve your fuel efficiency in a Prius
(if not any other car). Fuel efficiency tends to drop on
a Prius when the engine is run over 1/3 its max power
which on a ScanguageII is when the Xgauge GPH > 1.39.


hope this helps

Walter Lee
2010 Toyota Prius 3, oem floormats
Blue Ribbon/Dark Grey
Yokohama Avid S33 ( 50 psi front/48 psi rear )
ScangaugeII ( AVG/MPG, RPM/Fwt, SoC, GPH)
odeometer 13100 miles/ 59 mpg

 

need more info

What are you expecting and why?

You should really answer the above question and the questions at http://priuschat.com/forums/gen-iii...-answer-these-questions-esp-if-youre-new.html in a new thread if you want mileage help.

43 mpg might be the about the best you can do, given your driving conditions, esp. if they are short trips.

 

The main reasons I got a Prius were similar: it suits my needs, even at EPA it gets great MPG, and I was curious to see what hypermiling it would deliver in my usage.

From hypermiling an Insight-I and a Subaru over the past 5 years, I don't find the Prius is easier or harder to hypermile: it's just different. It's harder for me to figure out what is going on (so I got a Scangauge to see if the ICE is on) and as with any CVT it's difficult to manipulate the rpm of the ICE and the load on it. My impression is that Toyota tried to make it relatively easy for people to get EPA MPG in the Prius (though some people don't!), and in doing so made it trickier to get great MPG.

As you say, MPG depends on so many factors, but a huge one (for any car) is how the driver drives it. So I don't think the Prius has a top hypermiling limit of 65MPG. Everybody, even the most ardent hypermiler, has a limit to what they are willing to do in terms of safety and effort, and that limit determines the max MPG they can get. For example, I'm not comfortable going <50mph on a 65mph-limit interstate (unless there is no traffic behind me or I am in a climbing lane). At 40mph I'd probably get higher MPG, but that seems too scary for me. OTOH someone who insists on driving "with the flow" at PSL+10 because they think it's unsafe to go slower (or they think going slower will add too much time to their trip) will get lower MPG. As someone pointed out here, that's why laws of physics are laws, not suggestions.

My experience confirms most of the rest of what you say, with a few comments:

Para 1: STM the MPG "hit" of warmup lasts only until the ICE reaches operating temp (Scangauge). From there, my trip average MPG rises continuously over the next hour or more, which means that the car is already running at high MPG's and gradually "amortizing" that hit. Maybe you meant that the trip average MPG rises to your max level over that period of time.

Para 3: To me the optimum terrain is not flat, it's gently rolling, or even better modestly steep uphills followed by long gradual downhills. You can run the ICE in an efficient range climbing and then either shut down or run at very high MPG for long periods on the downgrades.

Para 7: The OEM tires are LRR, no??

Para 8: So far STM it's advantageous in the Prius to run battery-only in light load conditions (flat or gradual downhill) and let it recharge the next time the ICE comes back on for a hill or an acceleration. Hopefully the recharge load adds to the propulsion load to put the ICE into an efficient fuel-burning mode, and no energy is wasted spinning the ICE under light load conditions. Any MPG "hits" during recharge seem to be outweighed by the MPG gains during battery-only (talking about speeds <45mph here).
[In the Insight-I it seems to work best to keep the battery fully charged, so that's different.]

Para 9: I agree with everything except constant speed. Huge variations in speed are of course not advantageous. But I set a mental speed "goal": on secondary roads it's the speed limit, on highways it's usually 50mph in the right lane. Then I let that my speed fluctuate a bit around that goal as terrain and traffic dictate. Going up a hill, I might let it drop a few mph over the crest, especially if I know there's a nice downhill afterwards to regain speed. If I gain too much speed on a downhill, I add in more regen with the brakes or "B", no point in throwing away energy to aero drag. If no one is behind me, I may let the speed droop a bit if that seems advantageous; with following traffic I try to stick closer to my "goal" speed (in the right lane on multilane roads of course!). I may ease off a bit to build a "cushion" between me and traffic ahead of me so I don't have to lose too much momentum if they slow to make a turn, etc.
[I'm aware of P&G and used it a lot in the Subaru. Haven't yet figured it out in the Prius!]

Thanks for the writeup, it's very useful!!!

P.S.:This is oh so true:

People have such a hard time accepting that:
(a) A car's MPG is not a single number, or even two: it's a range. Different Insight-I MT owners see anywhere from 40MPG to 95MPG, so they are used to this concept.
(b) The largest single factor determining where one's MPG is in that range is how one drives. People think that changing gas, different tires, airing up the tires, using a grille block, a new air filter, adding aero mods, etc will radically change the MPG they get. These things can help, but driving the car the way it was designed to be driven will help even more (and costs nothing).
(c) Driving this way is enjoyable and relaxing. Comments on here about "just enjoy the car": I absolutely do! People who haven't actually tried it think hypermiling must be boring or stressful. It's a lot less stressful than driving 80-85mph as I used to do!! But hey, if folks want to drive as they have always driven that's fine too - just don't complain about your MPG!!

 

Wow... VERY informative posts...

 

The Prius main computer is always trying to optimize fuel
efficiency so to be truly effective a Prius hypermiler
must apply only techniques that work in harmony with
the main computer's programming. The challenge is
that the Prius is constantly fine tuning the electric
motors and the gas engine outputs - the HSI indicator
only shows the driver a composite effort by three
powerplants (ICE, MG1, MG2). It seems I'm always
trying to play catchup...

Clarification: What I meant is that the current top
*overall practical* hypermiling limit is about 65 mph.
I can get +75 mpg on some route/trips but I can't
consistantly achieve that level so my overall MPG is
more like 59 mpg. My mpg varies too. In the winter it
was 52mpg. In the Summer/optimum weather conditions-
it can be as high as 66 mpg.

Para 1: In the Summer/Spring/Fall - Yes, once the
ScangaugeII/FwT >= 181 the ICE stays warmed up and
the ScangaugageII/AVG is "amortizing" the MPG hit
from the cold start cost. During the summer, If
the Prius is turned off for less than 15 minutes
and then turn it back on - the engine is still
warm and the "amortizing" continues ( the cold
start cost is mitigated). During the Winter when
the temperatures are less than 30 Farenheit degrees,
the engine temperature can drop because of a stop-idle
(traffic light/jam) or because you are running
only the electric motors (Steath highway mode,
GPH=0.02). When the temperature drops below 130 F,
the Prius will automatically turn the ICE on just
to warm up the coolant temperature to keep the
catalytic converter hot. This inturn can cause
your fuel efficiency to drop like a rock (this
happen to me when my Prius was stuck for one
hour in a traffic jam caused by snowstorm - my
Scangauge/AVG dropped from 55 mpg to 22 mpg for
this particular trip primarily because I was
running the window defrosters to occasionally
lookout the window).

Para 3:
The best way to approach hills is to synchronize
the Prius acceleration with the downhill grades
using that speed/momentum from the downhill approach
to assist the Prius's efforts going uphill.
For short uphill section, I apply just enough
power from the ICE to assist the uphill climb
until the Prius is near the crest of the hill.
For larger longer uphill sections, I gradually
decrease the speed of the Prius from the
middle of the uphill section to the top of
the hill - to decrease the fuel consumption.
When the Prius gets to the top of the hill
the ICE should be be about 10mph less than
when it was at the bottom of the hill
However, it seems to me that the original poster
wasn't a hypermiler candidate so I was thinking
that the above technique wasn't going
to be something he'd agree to.

Para 7:
Unfortunately no. :-(
My OEM tires, Yokohama Avid S33, are not considered LRR atleast
by the tire industry. Yokohama (as to other Tire Manufacturers)
do make LRR tires but they are more expensive ($_$).
However, if I overinflate the Yokohama Avid S33 to 44psi or 50psi
their rolliing resistane decreases to a level similar to that
of the more expensive LLR tires. Increasing the tire pressure
from 35/33psi to 44/42 psi increases the Prius's potential
coasting ability and thus contributed to an overall summer
fuel efficiency increase from 55 mpg to 65mpg. However,
Overinflating regular tires at 44 psi and above will result
in more road vibration/shock being transmitted from
the tire into the cabin so the Prius ride becomes harsher.
When the tire pressure is increased above 50 psi
the rolling resistance is less than if 44 psi but there can
be a small loss in road traction/grip at higher
speeds and when the road surfaces are wet/slippery (which
a driver must anticipate and compensate for).

Hypermiling expert Wayne Gerdes has overinflated tires
up to 80 psi in a recent hypermiling contest - however,
I am not sure how significant the MPG benefits are
for going that high and what handling/performancee/safety
driving limits/precautions should be observed at that
tire pressure setting.

Para 9: I chose constant speed because I didn't think
the original poster would be more amiable CC than to P&G.

I concede that P&G is better at optimizing a
vehicle's kinetic energy than a constant speed.
It also take less power to accelerate a Prius
as it moves downhill than when it is moving
on a flat road or while driving uphill (because it
requires less power/torque to push the car downhill
than uphill/flat straightway). The most fuel
efficient way to handle hilly terrain is to
uses the increase motor efficiency going downhill
to negate the increase motor load going uphill.

(b) The Prius is already very aerodynamic so
aero mods like changing the roof antenna don't
increase its MPG significantly. However, for
non-aerodynamic vehicles, aero mods can improve
vehichle's highway fuel efficienct significantly.
For example, adding aero mods to a pickup truck
(which normally have terrible aerodynamic characteristics)
can increase its highway fuel efficiency significantly.

(c) I liken hypermiling as more akin to sailing a boat
- there's a kind of attitude where the driver
is working with his environment to move forward.
The original poster appears to be more of the
motor/speedboat pilot variety where the driver
is limited to manipulating the vehicle's power
source to move forward.

 

I rented a Prius in Jacksonville, Fla. (cost me $540 for a week!) just to see what kind of experience/gas mileage I'd get. I drove it about 800 miles and the first tankful gave me 48 mpg calculated. The second tankful gave 43 mpg calculated. The car was kinda fun and I enjoyed the experience, although I thought it was slow off the line unless I stomped it. But nobody ever said the Prius was a hot rod. I didn't think it was worth $26,000, but beauty is in the eye of the beholder, I guess, and dealers charge what the customer is willing to pay. I'd have to think twice before I'd spend that kind of money, especially when the VW tdi and Mini are right up there too, mileage-wise.

 

Prius doesn't start at $26K. It starts at an MSRP of $23,520 before dest charge.

If you go w/a VW, you'll have the "fun" of the lack of reliability of them. Diesel is more expensive than regular gas most of the year (see www.fuelgaugereport.com and http://www.eia.gov/tools/faqs/faq.cfm?id=9&t=5). The '11 Mini Cooper in the comparo and per Side-by-Side Comparison requires premium gas.

Those vehicles are also quite a ways from the Prius in combined mileage. Per Side-by-Side Comparison, '11 Jetta TDI auto is EPA rated 34 mpg combined and Mini Cooper 31 mpg combined vs. 50 for the Prius. That makes the Prius 47% and 61% more efficient, respectively.

 

Cwerdna is right about all. The Prius is the highest rank and the MINI is the lowest raking vehicle.
VW is a bit better, but still below average.




Videos - Free video downloads and streaming video - CNET TV

 

I will vouch for the crappy reliability of VWs.. I had a VW Golf and an Audi TT.. I have NEVER spent soo much in maintenance my entire life.. EVER.. I will never go back to a european car again..

 

Would I buy again? YES! As soon as the plug-in comes out in my region! Maybe the Prius C as soon as it comes out. I have always gotten over 50 mpg. Presently at 54 mpg. I don't drive like a grandma and have gone over 100 mph! I don't like the dealerships around my redneck area but then again they are rednecks! Just logged 15,000 miles.

 

From Walter Lee.

I insist on going the flow of traffic because if I am dawdling along trying to save a few tenths of a gallon here and there, I am causing density waves in traffic, which causes other drivers to slow down and speed up as they have to change lanes to get around me, and I thereby cause other drivers to use many more gallons of gas doing this than I would save if I stayed in my own world. Most car accidents on the highway happen in these density waves, so there is also a potential for that as well.

 

Ewww, I had a new beetle years ago, and I never had so many problems with a car. I spent months waiting for a door lock mechanism to come in from Mexico. The Parts Manager got tired of hearing from me, and he said he would never own a modern VW because of reliability and parts issues.

 

Driving in our Prius in outskirts-of-city type speeds (i.e. traffic lights but no gridlock and no highway speeds) with the AC on this past week I'm having to consciously try and maintain even 47 on the computer--that's about 45 mpg real world. This does include the occasional hearty acceleration (as should be expected), but lots of early braking to maximize regen. I really can conclude that the EPA 51 is not realistic for this car. I am all but positive that the _average_ driver of a 3rd gen prius is not consistently seeing 50-53 on their computer per trip as they would need to be equivalent to EPA.

Yeah, I know some of you claim 70 mpg is easy or whatever but I'm talking about the rest of us.

 

TRAFFIC WAVE EXPERIMENTS

Oh, and it's a LOT more than a few tenths, more like 10-20mpg on the highway, perhaps 10mpg in town. Without AC. The one time I used AC I set it at 75 degrees, the dehumidification helped a lot, and I didn't see a big effect on mpg.

 

vw car is absolutely trach and it won't ever stay with you more than 3 years then you'll spend a lot of money in it

i would buy the worst totoya car ever than buying any germany car :d

 

Maybe I'm fortunate to live in a region where PSL, while slower than the mean, is still within the normal speed spread. And it helps that a portion of the CDLs are obeying PSL as a condition of employment.

Bob Wilson's MPG vs. MPH graphs show far more 'a few tenths of a gallon' to be saved by not speeding.

It is no surprise that most crashes -- the 'accidents' euphemism just obscures the causes -- occur where most of the car are. But the local reports often list specific driver misconduct, and I'm not detecting any pattern of what you claim. Nearly all the local crashes related to someone not moving 'with the flow' involve a victim not moving at all, e.g. disabled vehicles along the road, or the trooper and the suspected DUI he was arresting last weekend, hit when yet another DUI slammed into both their cars.