Prius overall MPG shows no improvement in the 3rd generation according to Consumer Reports tests

Perish the thought!

Wayne: Are you getting the same mileage, overall, in your 2010 as you did in your GenII?

 

I'll disagree with this, as I don't believe the CR tests or figures are in any way normative. I think much of the rest of what you say (regarding both CR and EPA testing) is a better way of looking at any single-party test of mulitple vehicles.

Yes, your driving habits could (likely will) result in different FE numbers. Again, I don't believe it is appropriate to see the CR numbers as "actual MPG he/she can expect" to get in inner-city driving.

I don't think the CR numbers are any more reliable than the EPA numbers -- except for the purpose of comparing one vehicle to the next. Hybrids, especially the HSD-type such as the Prius, will show significantly better fuel economy with longer drives. This means the tests may not really be the best comparisons among cars when hybrids are included, but it is at least a common baseline. In fact, this is the only thing I'm really looking at when viewing the CR or EPA numbers: How does the Prius stack up in comparison to all other vehicles who've been subjected to the same protocol.

I don't know exactly how CR does it, but I believe the EPA protocols produce reproduceable and consistent numbers, regardless of the driver. What I don't know about CR is whether they require a consistent acceleration among drivers or over certain parts of their course -- and whether it is measured. This will significantly affect the reproduceability of their test results.

Still . . . How could CR get the same numbers for the 2010 and for the GenII? One thing is for certain: They haven't been able to drive the 2010 in all conditions!

For me? My 2010 gets better gas mileage. I have the 2010 Prius V w/ AT, so I expect I get lower mileage than those with the other 2010 models. I haven't yet driven my 2010 through a full year, so a true side-by-side comparison is a bit difficult. I have compared the first couple of months of FE in the 2010 to the first couple of months of FE in the 2007, and the 2010 came out way ahead.

We will see what happens over time. I expect I'll be showing both numbers in my signature for some time.

 

I think CR or EPA MPG ratings are only useful as a comparison between cars. Every car's fuel efficiency is subject to the drivers driving style, so those tests should not be used to make personal assessment as to what kind of fuel mileage you will get.

Obviously some drivers who treat the Prius like a rice rocket only get low 40s, while calmer drivers get mid-high 50s. Remember, you are the pilot and you have a major role here in terms of how you want the car to perform.

 

I'm an Insight owner crashing your forum


As most of you probably remember CR absolutely blasted the 2010 Insight. Insight owners were pretty shocked by the terrible review - most of the complaints that CR aimed at the Insight were confusing or completely nonsensical. The most puzzling part of their "review" was the mileage - they averaged 38 mpg. Insight owners, myself included, are easily (ie. no driving like a hypermiler) achieving mid to upper 40s and are consistently hitting 60 mpg in town. Some people have went out of their way to "kill" their Insight mileage and still have difficulty getting under 40 mpg.

I have to admit, no offense intended, that CR's less than favorable review of the Prius is a bit of concillation for the Insight review. The Prius review is more kind than the Insight review but hardly what I would call a good review. It seems that CR either has it out for hybrids (let's call it the Jeremy Clarkson Syndrome) or they have no freakin' clue how to drive one.

I've never taken CR's car reviews terribly seriously (I think they should stick to toasters and ironing boards) but these two off base reviews are the final straw. They have become useless to me. Unfortunately though, many people view it as almost a Buyer's Bible and will look at no other sources when making a car purchase.

 

There are numerous types of 'city driving'.

One of course is the EPA test methodology.



Then there are three types in what was my normal commute from the Jersey suburbs to lower Manhattan..

• crawling 'on the highway' down the FDR Hwy at 10 mph
• driving normally across town on one of the numbered streets from stop light to stop light to stop light.
• rolling slowing in heavy traffic uptown or downtown along one of the avenues catching most of the green lights

Then there is suburban 'city' driving in normal traffic at 30-50 mph on suburban roads.

Then there is driving in your neighborhood where the speed limit is probably 25 mph Max with numerous STOP signs at the intersections.

Take your pick.

The big hurdle than cannot be overcome in any type of 'city driving' is coming to a dead stop at a light or a stop sign. This impediment is Newton's first law of physics. If at all possible NEVER stop.

A month after getting mine back in 2005 I took it on a model spin to see what the best capability was. For a 50 mile 'city' drive I took it along the beach on the Outer Banks at 25-30 mph on a quiet Sunday drive with no pressure....and NO STOPS... and achieved 65 mpg for that loop.

Then I replicated my 1980's commute from NJ to lower Manhattan.
At 65 mph on I80 Eastbound to the GW Bridge....50 mpg
In Stop and Go on the FDR...55 mpg
Going East to West on 49th St - hitting every light - 35 mpg
Going North to South on 7th Ave - rolling constantly - 70 mpg

 

Welcome. I think you've already found that the response from Prius owners is not too dis-similar than the opinions offered by Insight owners. We have to remember, of course, that those of us participating in such sights are really enthusiasts who likely are more interested in finding out how to maximize mileage. CR testers don't necessarily share the same concerns!

 

Consider CR a resource only! What really matters is what YOU experience. Personally, I did not have a G2 ... so it is a mute issue. But, I do achieve better economy than the EPA figures ..... As long as I can maintain that ... I am absolutely delighted. Isn't that really all we should hope for. Forget what CR says, or other drivers for that matter. There are so many variables, temperature, tires, elevation, gasoline, but especially driving habits.

 

Definitely. I'm sure people that take the time to register, read and post on sites like this and InsightCentral.net are not the average car buyer. That said, I do think that hybrid buyers as a whole realize that there is some trade off for the higher mileage of a hybrid. You aren't going to be able to drive in the exact same way you did in a regular non-hybrid vehicle. It took us a few days to greatly improve our mileage with little things like coasting to stops, easing up on the gas when accelerating, using the AC sparingly, etc. Nothing major but definitely things that make differences. My guess is that CR did not do any of these and drove teh Prius and Insight like they do any other car. That's a shame because it is a way that highlights the weaknesses of both cars and all but ignores the strengths.

 

I guess I don't understand the fuss. I am a first time Prius owner with 900 miles on the OD. I have 50/50 city and highway driving and my overall mpg right now is 50.1. I have kept the mpg manually as well and it comes out to the same thing. Longest trip has only been 149miles and got 56.7. The highest was just today, 7 miles mostly on the freeway with about 2 miles in a quiet community and went over 60mpg for the first time. I AM NOT a hypermiler, I drive normally like I would in my mercedes. I enter traffic quickly and I pass w/Power often but then drive most of time at speed limit with the info bar within the ECO area. I am more than pleased so far.

I think one of the secrets is that you don't baby it and try to go too slow when starting from a stop. Start out fast and get to speed quickly and then moderate the pressure on the gas pedal so that you see that bar hang out up around the 100mpg peg. At least try to keep it between 50 and 100mpg. I don't know if that is hyper cruising or not but it is easy to do and I don't even think about it anymore. I just drive.

 

As we established earlier, they do NOT and it's by design.

Nope, they don't, see above.

http://priuschat.com/forums/other-c...uth-about-epa-city-highway-mpg-estimates.html and http://www.consumersunion.org/Oct_CR_Fuel_Economy.pdf which I posted earlier in this thread should give you both and others here some insight into the EPA's and CR's tests.

Regardless of whether you agree w/the final outcome, it does make some sense. The tests (at, least the EPA ones) are repeatable and have very specific conditions and requirements.

Are the EPA or CR supposed to try to find the "optimal" way/speeds to drive each car? If so, how closely do they reflect ACTUAL, reasonable driving that doesn't piss everyone else off? How likely is it that a consumer will even do this?

Reporting numbers that are too high causes people to be disappointed when their numbers aren't even close. People will say things like the numbers are bogus, inaccurate, too high, etc. (How about the 89.4 mpg on the Japanese 10-15 cycle? How easy is it to achieve that in actual driving?) The EPA has changed their method 2x: once in MY 2008+ and another time in the early 80s to tack on the 10% reduction in city and 22% on highway.

My mom can't be even bothered to measure her mileage. She just flat out refused to in her old (now totaled) 96 Camry and her 07 NAH.

How far should a publication go? Let's say they arrived at 50 mpg overall on a 2nd gen Prius? Is that good enough? Some folks here get over that on their 2nd gen. What about 60 mpg? That's tougher... But some might say, no that's still not good enough until they reached 110 mpg.

 

CR has consistently rated the Prius at the top of the cars in its size class. And it's readers' polls have shown Prius at the top in reliability, along with other Toyota and Honda cars. The polls are based on reader feedback, and so not prone to subjective analysis.

The thing that bugs me is how those expensive German cars, especially Porsche, can have such lousy reliability. That's inexcusable, especially considering they are dreadfully expensive to repair. Porsche and BMW come to mind. Dealer service on those cars can be robbery. Don't ask me how I know.

Back to Prius, I didn't understand why there was so much distance in the CR ratings of the Touring and regular cars. Touring cars are rare in my area, and my regular 08 Prius handles just fine, as long as I don't drive it like a sports car--which it isn't. Steering response and handling are a whole lot better than a Ford Escape hybrid, which I have also driven.

As far as CR's gas mileage numbers are concerned, they are only useful as a relative comparison of different cars. They low-ball my actual driving experience for several cars I've owned by 15-20%. In spite of these things, I still think CR is the most reliable tester out there. They are the most objective, since they are the least dependent on car industry advertising.

 

Two observations:

1. CR and other "objective" testers have to use the same protocol, otherwise the comparative value doesn't exist. I have read about the EPA protocol, but not the CR one (thanks to Cwerdna for the new reference on that one).
2. Wouldn't it be interesting to see the EPA (and/or CR) ratings on other cars if they were driven the way you now drive your Insight? With the correct techniques, ANY car can show a significant improvement in FE. In fact, anyone using those techniques should blow away the EPA estimates in any car -- hybrids included!

 

Don't know about the Gen II vs Gen III but my '04 MFD runs about 2% generous (basically 1 MPG), where my wife's '06 runs 4% or 2 MPG generous. Plenty of miles on both cars to say this is consistent between THOSE 2 cars.

On the other hand, my speedo reads about 1 MPH low at 30 MPH and 2 MPH low at 65 MPH and hers is right one straight through.

 

BUT - you can and SHOULD do all those things in ANY car. The benefits are just a lot more obvious when your car gets 50 MPG instead of 20 MPG and you have a display that shows instant feedback of your actions.

What you CAN do in a Prius (and Insight or not??) is slip into 'glide' where there is no power to the wheels or regen braking. It is almost as if you shifted to neutral. You can 'coast to a stop' from much farther back (using NO gas or electricity) since you aren't slowing quickly (presuming not going uphill).

Oh yeah, and welcome

 

I agree with CR. My city mpg has been definitely and obviously worse than freeway mpg. 46 in mostly city (2 people and with AC on) and 48.8 on the freeway so far. My Prius has only around 600 miles.

 

It's hard to reconcile ... CR had no problems obtaining Gen II earlier 50-60mpg results before EPA made things harder. Now, they can't do better? What ... did they hire new people?

 

Lets start by looking at the respective CR test protocols.

CITY

• stop-and-go on test track
• 18 stops
• 4 minutes idle time, total
• 40 mph top speed
• 6 trials
• 2-minutes, 40 seconds per trial
• 16 minutes, total time

So 6 x 2:40 = 14:40 of trial time. This gives 16:00 - 14:40, about 1:20 for driver changes, pauses, cuppa coffee, e.t.c.

Analysis

The CR total time, 16 minutes, is not enough to warm-up the car.

My NHW11 typically takes 15-20 minutes to warm-up. The engine is up to 70C in ~5 minutes for hybrid operation but it still takes almost another minute to reach the normal 85C. But full vehicle warm-up should include the transmission and tires and that easily takes 20 minutes (more when colder.) Vehicle transmission and tire warm-up is a very hard thing to 'adjust' when the vehicle has been cold-soaked at temperatures below 50F.

The old EPA test duration was 31 minutes. The vehicles had a chance to run at least 10 minutes, 1/3d of the test, fully warmed up.


HIGHWAY

• Central Connecticut State Route 2
• 5 mile, 65 mph runs
• 8 runs
• 4:38 per run
• 37:00 total time

Analysis

Shorter than I care for but not 'setting my hair on fire.' I find it takes 10 miles of highway mileage to get reproducible results with a running start (i.e., not including acceleration and decelleration.) The 4:38 is consistent with 5 miles at 65 mph so this is a running start. So they are close to 10 miles in the round trip.

I checked the terrain around central Connecticut and looks to be rolling hills along Route 2 but well away from the mountains. We'd really need better start/stop locations but Google Earth, flying the hand, it is OK. I really don't see a problem with their highway test other than I'd prefer it be a little longer and prehaps a little flatter highway.

Bob Wilson

 

So basically, Bob, CR are failing to control temperature and head/tailwind effects at their test track, and temperature, head/tailwind effects, and traffic, on the highway test. They say they adjust for temperature but how can they know exactly how each vehicle will perform in different temperatures?

There is a reason that the dynamometer test is the gold standard: it's that as many variables as possible have been eliminated. The EU test even dictates when the gearchanges should be made and which gear each part should be performed in, for manual cars. Unfortunately the very control over those conditions makes the results less likely that any driver will actually achieve those numbers under normal driving conditions. I'm surprised that the EPA hasn't nailed down the temperature for the city, highway and high-speed tests: a range of 20-30°C (68-86°F) is still permitted.

The modern EPA estimate is beatable for two reasons. It contains fixed discounts from the dyno results, and it now contains two incompatible test conditions: cold temperature running at 20°F, and air-conditioning use at 95°F.

EU tests come (as far as I know) straight off the dyno, are artificial, don't include high-speed running, are carried out hot, and don't include AC use. As a result, the identical new-model Prius gets 20% higher results than the EPA test. Same car, different test protocol.

 

No. Cold engine is not one of the biggest characteristics of city/urban driving. It is critically important when looking at short commutes, but that is about all. Engine temps can get very high, very quickly in city driving. The stop and go world provides little airflow for cooling, and the repetitive acceleration combined with A/C demand also can get the engine cooking. The problem is that for people who have commutes twice as long as the CR test, will think that they are going to get only the CR number, when they are likely to get much higher -- due to the second half of the run being on a (mostly) warm engine getting significantly better MPGs.

The two obvious problems here are: (1) You will never really know that you've just replaced exactly the same amount of gasoline as just used; and (2) If the car's computer is wrong (and it is using the odometer for the numerator), how can you trust the car's odometer reading? I understand you are referencing this in the calibration issue, but how are you really going to know these numbers?

Truly, the MPG world can only be looked at, realistically, by doing long-term, multi-tank readings (again, as you've suggested). It also can only be on a relatively gross scale, anyway. I do report MPGs to a tenth of a gallon, but I don't know how realistic that is. I get numbers with even more [significant??] digits, but do I really believe those are significant? No.

So perhaps I should say that my current mileage (based on the MID data) is 59 City, 56 Highway, 57 Combined. (By my per tank calculations I get 54 MPG combined -- I don't fillup at each urban/highway change.)