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

This also touches on the reason why it's difficult to compare fuel economy of different vehicles based on anecdotal owner reports. The demographic of buyers can vary considerably, even among similar types of vehicles. Witness the IIHS driver death and injury rates that sometimes varied significantly even among corporate twin models. The driving habits of Prius vs. Fusion vs. Insight vs. Civic vs Altima hybrid drivers could vary along with their age, income, education and many other factors.

Other factors may contribute, also. One group may be more likely to over report mileage, another to underreport. This is a similar potential flaw to the voluntary, self reporting of reliability issues from an unscientific survey like the one CR uses to poll only its own subscribers.

So, while the subset of car owners who participate on internet forums is interesting as one method to compare fuel economy (or reliability or whatever) it may not always be very sound, statistically.

Obviously, we have the EPA numbers from controlled testing. Soon we will have CR numbers for Prius. It will be interesting how the two correlate on a percentage basis. Are their others? Do any of the other auto rags to a comprehensive fuel economy test that they perform in the same manner for a direct comparison? Controlled tests have their own set of flaws mentioned in this thread, most notably that the test drivers may not maximize fuel economy like a typical hybrid driver. I know a few comparison reviews exist from the likes of Motor Trend, Edmunds, Car and Driver, Popular mechanics and others. It would be interesting to see someone compile a list of all such test results. Anyone have that?

 

Darren, a couple of years ago I sat down and made a list of competing apples_to_apples comparisons then available. Although I saw an occasional outlier, *in general*, similar differences were found -- as expected. If memory serves me, I looked at the city Japanese cycle, EPA, Europe, and CR.
Someone posted earlier that only dual G2/G3 owners could reliably answer whether mpg has improved. I can think of a number of reasons to doubt this sort of approach:

• To the extent that driving experience matters, the G2 has an advantage.
• If the G3 is improved in certain areas only, then an anecdotal driver will only find improvement if their driving matches the area of improvement. It is even not unreasonable to think that certain driving conditions tend to worsen in the G3 due to it's bigger engine and higher weight.
• People want to think that their purchases were of value. I personally would find it hard to not hypermile a little more in earnest in a G3.

My take: if the results are close between the cars, then it suggests that YMMV, and each person will do well to match the best car to individual circumstance. I still think the G3 is going to shine in the winter compared to cars that do not block/preheat.

 

Don't want to be too picky, but my suggestion was this: "If you are willing to trust self-reported numbers like these (on the fueleconomy.gov site), then perhaps it would be better to ask GenIII owners who've also had GenII cars to report comparative fuel economy numbers."

I think the GenII numbers are going to continue to improve as the cars age and the drivers gain more understanding as to how they can increase fuel economy. So, for the time being, the GenII numbers will be closer to a plateau than the GenIII numbers. Yes, GenII cars will have that advantage.

Perhaps the GenIII will perform better in certain areas than others. It also may outperform the GenII in some, none or all of those areas. My opinion: Better to look at two different cars through the eyes and driving experience of people who have or do drive both of those cars in the same fashion in the same area and in similar circumstances.

Question whether dual owners would attempt to justify their GenIII purchases by being better drivers (for FE purposes, anyway) in their GenIIIs than in their GenIIs: I can't suggest we ignore human fallibility -- that's one reason I'm not so confident in a small amount of testing by CR in advance of this report. Still, I think I was doing more (hypermiling or something like it!) of this with my GenII than with my GenIII. (A good example of my own interference with things!)

A better option, perhaps, is to see long-terms studies by "objective" persons who have used both generations in or under all different circumstances. This hasn't happened (yet, anyway). What HAS happened is that a large number of us who've had both cars have now been able to say (if nothing else) which car gave better fuel economy numbers under two- to three-month uses.

 

Don't want to be too picky, but my suggestion was this: "If you are willing to trust self-reported numbers like these (on the fueleconomy.gov site), then perhaps it would be better to ask GenIII owners who've also had GenII cars to report comparative fuel economy numbers."

I think the GenII numbers are going to continue to improve as the cars age and the drivers gain more understanding as to how they can increase fuel economy. So, for the time being, the GenII numbers will be closer to a plateau than the GenIII numbers. Yes, GenII cars will have that advantage.

Perhaps the GenIII will perform better in certain areas than others. It also may outperform the GenII in some, none or all of those areas. My opinion: Better to look at two different cars through the eyes and driving experience of people who have or do drive both of those cars in the same fashion in the same area and in similar circumstances.

Question whether dual owners would attempt to justify their GenIII purchases by being better drivers (for FE purposes, anyway) in their GenIIIs than in their GenIIs: I can't suggest we ignore human fallibility -- that's one reason I'm not so confident in a small amount of testing by CR in advance of this report. Still, I think I was doing more (hypermiling or something like it!) of this with my GenII than with my GenIII. (A good example of my own interference with things!)

A better option, perhaps, is to see long-terms studies by "objective" persons who have used both generations in or under all different circumstances. This hasn't happened (yet, anyway). What HAS happened is that a large number of us who've had both cars have now been able to say (if nothing else) which car gave better fuel economy numbers under two- to three-month uses.

2300

 

Well, the mpg data from Flying White Dutchman's pole "correlates" perfectly with the EPA data. So there isn't anyone trying to skew EPA's data. I also believe Insight's data is also not skewed.

See Bob Wilson's plots and see for yourself. I wish the Insight data is also on the graph.

 

Actually I have detailed mileage records for my 1.5L NHW11 and compared the first 90 days with our 1.8L ZVW30:

	Column 1	Column 2	Column 3	Column 4	Column 5
0	model	miles	MPG	comments
1	NHW11	3	700	48.1	spans October 10 to January 10
2	ZVW30	4	000	52.9	spans May 27 to August 27

.
We are finding the ZVW30 is roughly +5 MPG over the NHW11 with significant improvements in creature comforts and avoidance of high speed mileage loss. We still have both cars and I'm driving the NHW11 to work and using the ZVW30 for home chores and day trips. Best of all, I leave the ZVW30 at home so my wife can safely and efficiently drive where ever she needs to go.

FYI, my latest fill-up from the weekend and around town driving:

• 117.2 miles :: 54.3 mi and 62.9 mi.
• 1.747 gal (pump) :: 0.76
• 67.1 MPG (actual)
• 80.5 and 71.44 (indicated, two segments)
• 19 and 20 mph

It looks like performance has dropped off but I was doing more stop and go driving and dealing with other traffic. This was running errands around town and not just test loop drives.

Bob Wilson

 

I don't quite understand why you've posted the reply to me.

I'm not the one arguing that user-posted data doesn't have any value.

The entire purpose of my posts in this thread has been to suggest that real owners/drivers of both the GenII and GenIII are the better evaluators of whether the newer Prius gets the same or better mileage (fuel economy) than the most recent past version. I'm more than a little uncomfortable with CR's very short test session, and I'd much prefer to see longer-term tests using the same drivers over similar routes.

I am so vocal on this because of my experience. I drive the same routes (mainly) the same way. The fact is that I have driven my GenIII with less attention to maximizing fuel economy, but I have seen better numbers than I did with my GenII -- even when my 2007 was broken in and getting its best mileage. And all of this with the 17" wheels on my Prius V!

Certainly, my own experience makes my position a bit biased, but I haven't yet heard anyone say they have a GenIII that gets lower mileage than a GenII. I think I read a post of an owner who gets the same mileage (roughly) in both (this matches the CR report), but by a large margin the people posting on this subject are reporting as I have -- the GenIII gets measureably better FE than the GenII. And the cars aren't even broken in yet!!

 

consumer reports has always sucked lol.

 

Me too!

 

Here's my input, having owned a Gen 1, 2 and 3.

In just two fillups for the Gen 3, both (56.5 and 58.5 mpg) have been better than any fillup in the Gen 1 or Gen 2, ever. (except a couple of bogus ones where the pump shut off too soon and the mpg was unexpectedly high then confirmed by low mpg on the next tank). More time will tell, and of course summer driving is the best mpg.

Perhaps the Gen 3 gets its best mpg for my particular commute. That is about 6.5 miles each way, ~20 minutes, about 2 miles of 35 mph roads, 4 miles of 50 mph (where I can usually go slower for 1-2 miles) and 30 mph for the last .5 mile. Then reverse going home, but ~2 days a week of a side trip to the gym (3 miles) then home (7 miles) on a better route.

Much shorter trips still cause mpg to suffer, but my "medium" sized city trips seem to show that the quirks of how the hybrid warmup cycle has evolved is getting better and better, IMO.

3PriusMike

 

my 04 with 17 inch rims gets only 40mpg.. a package V 2010 gets much better. just my $0.01 ( i was taxed )

 

I may be the person you remember reporting very similar results for Gen III as I had for my Gen II. I've had 3 fill-ups so far, with calculated results of 43-45mpg. As I have explained in other posts, my tanks have included a few 30-mile trips on the freeway, for which I could get 63mpg in one direction (apparently downhill) and under 50 in the other. However, my normal daily commute consists of 4 or 5 miles of uphill/downhill driving each way to and from the Metro station. In one direction, the trip display may show up to 52mpg, but in the other, less than 40.

The Gen III seems to warm up much faster than the Gen II, allowing it to achieve good gas mileage earlier in the trip. But it doesn't do any better going up hill than my Gen II, which is what is killing it. And I've really worked at trying to maximize my mileage (I keep up with the traffic flow though).

I haven't yet taken my new car on any long road trips so I'm hoping to see better results when I do. Shortly after I got my Gen II, I drove it about 600 miles each way for a work trip and got 55-60 mpg. Not long after that, took it on another long road trip for vacation and got great mileage. However, once I settled back into the normal routine of short commutes during weekdays with an occasional longer trip on the highway (similar to my current pattern), the gas mileage started going down. It did not magically improve after the 5,000-mile "break-in period." My final average over 3 years was about 43, which is about what I'm getting with my new car now.

Another improvement I have found is that my calculated mpg has been close to the displayed mpg on the new car -- all three fill-ups have been plus or minus 1-2 mpg of the displayed mpg. With the old car, I'd get big variations between the calculated and displayed.

 

No contest for me... I got 62.8mpg on my one hour trip in this morning.. the best I "ever" got in my 3.5 years of driving my GenII was 54.. and that was very rare... usually more like 50 - 52mpg

 

You may want to look at the calibration curve a bunch of us have been working on for indicated to actual MPG. You're mileage is still great, 62.8 indicated ~= 58.8 MPG, which easily rounds up to a +5 MPG increase. Considering how advanced the GenII is, getting a nearly 10% increase is an impressive engineering feat.

Bob Wilson

 

Plus we are comparing cars with 90K difference.. once the GenIII is broke in, I expect better.. I remember when I first got my GenII, I was around 46 - 47 at best.

I know it takes time to learn to drive with the software aids to improve your driving and I also got my car in January when the heater had to be ran more... but spring was soon to follow.

 

I did a Gen 2 vs Gen 3 test drive this week on my commute.
All conditions the same except maybe 3 or 4 degrees temp variation. Gen 3 wins by a lot...65 mpg vs 56 mpg. This is on a 6.5 mile commute each way.

3PriusMike

 

I am having a hard time understanding this discussion of genII vs Gen III mpg. We had a 2005 that was 3 years old(55000 miles) when we purchased it. We had it just over a year when we sold it and bought our gen III V. We drive the same route to our lake home now as we did with our GenII. Our new V is getting slightly better mileage than a well broke in Gen II. It is great to see the handling and other features of the Gen III and still getting slightly(about 1+ on a new car) mpg. I realize that we are giving up 2-3 mpg with the bigger wheels, but the way our new Prius drives is worth the small loss in mpg.

 

That sounds about right.. just according to paper alone... they do say a 3 mpg hit on bigger wheels.. "according the the chief toyota engineer".... that leaves you with only a 2 mpg improvement... that should improve even more as it gets broke in.

I wish I knew what the 17" wheels felt like, because I have no complaints about my 15"... the car feels like a luxury car and handles very well.

I don't know if going to bigger wheels would improve or worsen the ride.. but they put a tremendous amount of technology improvements into the 2010.. I was disappointed to only see a 10% improvement "5 mpg"... others say thats outstanding.. but I was expecting lithium and plugin etc too... so I guess my expectations were higher for a new roll out model.

I guess it is what it is.....

If it ever becomes an issue, I'm sure it would be easy to swap someone if you want the gas improvement.

 

Hi Alan,

I'm always interested in papers and articles. I don't remember reading this but it means I just haven't come across it. Can you point me to where I can read-up on this?

I'm running a test comparing 175/70R14 in place of my 175/65R14. The indicated MPG fell off by the expected 3% and GPS testing of tripmeter distance matches this expectation. However, the actual MPG is holding about the same, possibly ~0.5 MPG lower. But I didn't have a GPS with the 175/65R14s and had done only limited calibration with mile markers.

One other hypothesis is I'm probably running a little faster true speeds because I can maintain higher speeds while remaining in hybrid mode. For example, my indicated 38-39 mph is a true speed ~3% faster or closer to 39-40 mph. Over a long period of time, a year, this becomes significant.

Measuring the effects of small changes in tire diameter is not a trivial problem. The calibration alone requires a rigorous approach and I may be at the limits.

Bob Wilson

 

I agree... time always makes things significant!.... I have a friend who smokes and when he figured out he spends 5000.00 a year on 3 packs a day, we figured he could own a prius or similar with 5 year payments as 5 years of smoking added up to 25K... he was sick!...

Anyway.... those of us that went to Detroit purposely asked the chief engineer that question and most of the discussion I've seen centers around that meeting.

I doubt you will see anything from Toyota as it would be bad press.. but I could be wrong.

If I run across anything definitive I"ll try and post it.

Thats the very point I keep bringing up in the discussions as that one factor is so significant that every poll and every discussion needs to clarify which package they are talking about before they compare one with the other.