EPA MPG values reported for 2016 Prius very misleading

Lets not forget EPA figures are based on 100% gasoline 0% Ethanol.

 

maybe even a little nitro.

 

You bet they're misleading! I got 69mpg on my first tank and the car is supposed to get only 56! I'm going to sue Toyota!

 

Nearly 100% of Toyota's ads picture the 17" wheels.

They market the models with the 17" wheels as having the exact same mileage as those with the 15" wheels.

No doubt Toyota knows how to play the game within the rules, and are on the right side of all laws.

But if they know the difference to be real and significant (as seems to be common wisdom on Prius Chat) this subterfuge is still shameful.

It they are playing games with the Eco, even more so.

In the end they will probably sell more cars with their gamesmanship, so Toyota wins. But the truth and good ethics are the casualties.

Shame on Toyota.

 

There are going to be variables - and the biggest one is how the car is driven. The test has a standardised test formula of slow/fast, accelerating, cold start etc, but nobody would ever drive exactly that formula.

While Prius here in Australia is either of 2 versions with almost no options, when I investigated a BMW, the options list is HUGE, including multiple wheel options, and others which would effect weight like sunroofs - however, if you tick all the options boxes (and pay $$BIG$$), the MPG (l/100km) will be the same regardless - they're not going to re-test for my choice of options.

 

In the USA the 17" wheels are not simply listed as an option, but are a standard features of 2 particular models.

All 6 models are listed side-by-side in Toyota's marketing materials with all thier associated features and specs-- including thier MPGs-- listed for each.

Reading across the tables a buyer will take note that 5 of the 6 models get the same MPG, but one (the 2 Eco) does not. Buyers rely on that information-- I did.

The rules set forth by the EPA allow them claim that equivalency, but only because the standard features selected for each model were carefully picked. Had the weight of any of those 5 models varied much from the others, that model could have not claimed to have an equivalent MPG as the rest.

Unfortunately tire size is apparently not covered by "the rules"'. But assuming that Toyota knows full well that tire size has a significant impact on MPG (as seems to be common wisdom on Prius Chat), marketing those models as equivalent on such an important metric is misleading at best.

It's too bad that Toyotal has elected to show the best looking model in its mul-million dollar ad campaign, while allowing the consumer to believe that those good looks do not come at a price to the environment.

 

My Four, not IV because only 2010 used uppercase Roman numerals for model designation 2016 Touring, so far has great MPG. But I cannot compare it with a non touring 2016. Only my 2011, 2012, and 2009.
42 PSI folks.

 

ATHiker, I apologize to you for my flip remark earlier. I would probably be as upset as you are if I were in your situation.

Because I thought that it was such general knowledge that 17" tires will not get the "real world" MPG that 15" ones will, irrespective of the EPA ratings, I assumed that anyone who opted for a model with 17's had consciously decided that the extra features of the higher end models outweighed the lower MPG of the larger wheels. I stopped visiting PriusChat for 4 years, and one of the reasons I left was the endless handwringing by people wanting 17" (or bigger) tires and whether lowering the car might improve the MPG enough to offset the effect of the tires.

Also, MPG is a very slippery number because it is dependent on so many factors. For example, in favorable conditions I got tank MPG's in the high 60's in my Gen 3. And could not get out of the 40's driving city streets in Boston or using snow tires. Same driver, same car. The EPA numbers are just an attempt to get a number under one set of controlled conditions (with a tenuous connection to "reality") so that cars can be compared pre-purchase. Because MPG is more like a "range" than a single number anyway, the comparisons are not that exact.

One thing you could do is to buy a set of 15" wheels and LRR tires for your car. I'm guessing it might make a noticeable but not huge difference. The OEM 15" wheels list for $350 each and weigh 18lbs, so you probably want to pick out something cheaper and lighter at Tire Rack. You might be able to sell the 17's, or you could put snow tires on them and use them in the winter. I use General Altimax Arctics, and they are available in the right size for your 17's. In my Gen 3, my MPG took at least a 10mpg hit with them on, but in the winter not crashing takes priority.

I gather you are unhappy with the MPG you are getting. The usual laundry list of possibilities:
- The most common factor is driving speed. If you look at Wayne Gerdes' mpg vs speed plot partway down his report, you can appreciate how strong the effect is:
2016 Toyota Prius First Drive Review - First Drive Results | CleanMPG
And those are just steady state mpg's. At higher speeds you have to accelerate and brake more for traffic, so you are not in steady state..
- Short trips vs long trips - can't do much about that other than combine errands into one trip
- City vs highway vs moderate speed suburban - ditto
- Winter vs summer - ditto
- Staying in EV by careful application of load
- Obeying speed limits around town, constantly changing speeds costs MPG
- Tire pressure up to sidewall number
- Making sure the wheels are aligned
- Using AC only when you really need it, and then setting it just a few degrees below ambient: it will cool you by dehumidifying the air, running it like a refrigerator costs energy

Where in MA are you?

 

An alternate approach is to pickup the roll-down coefficients from the "Test Car Database" and using published and measured characteristics, generate:

Personally, I'm OK with a chart like this being required for each owner's manual. Solves the problem.

Bob Wilson

 

I seem to remember posts here from the 2009 introduction, where various invited PC members were able to talk with the Prius engineers. The overall EPA rating, not finalized at that time, was a sales-weighted average of the various configurations, including the larger wheel / lower MPG configuration. Some members even saw some of the spreadsheets being batted around before final equipment packages and tunings were settled.

There is room for gamesmanship in this, and it is clearly exploited by the industry as a whole, not just by Toyota. Kia, Hyundai, and Ford have even been forced to re-label some models, but I don't recall Toyota flunking any similar tests.

The gamesmanship in Europe has been even worse. Even before the VW debacle.

Lets also not forget that the 3% difference between E0 and E10 is tiny compared the kludgy empirical fudge factors used to derate CAFE ratings into the substantially lower EPA ratings. And that the 2008 revision of the EPA scale knocked off much more than 3% compared to the previous EPA scale.

 

Not so upset. As perhaps evidenced by my post count over the past 2 months, I absolutely love my car.

I came to the this site in 2010 to research a Curt hitch for my wife's Gen 3 but have not spent much time here since. (I only really caught the Prius bug after attending the 2 Go Before gathering that came to MA, and had just been visiting PriusChat to find out when we would finally get the Gen 4)

In a real way, I am glad I didn't know about the mileage penalty for 17" tire before buying my 2016 Touring. Sort of like having the pleasure of a delicious meal, and only learning that it was 2,000 calories after the fact.

In truth, I am just dissapointed that the marketing people at company that makes a great car still felt the need to craft a "truth" rather than letting a purer version stand for itself. They should be taken to task for that, at he same time we applaud the engineers.

As for my mileage, I am happy and understand there are many potential reason why different drivers get different results.

That said, I am interested in learning how each of those many variable impacts the total. Not out of bitterness but out of genuine intellectual curiosity -- and with an eye to finding my own balance.

 

keep in mind that this is true for (almost) all companies, and that first and foremost, they are in business to make a profit. then, you won't be as disappointed down the road.

 

Wheel diameter has to do with the mass location from the axis of rotation. The further out, the more torque and energy need to spin it up or slow it down. The 17" wheels and the tires weight more and their mass is further out. So acceleration and braking put a larger load on the car.

Bob Wilson

 

The Australian Brochure has a note referenced to the fuel economy "Fuel consumption and emissions vary depending on driving conditions/style, vehicle conditions and options/accessories."

 

that disclaimer should be on everything.

 

Make sense, but that begs the question: Why not go with 14" wheels and improve things further still?

 

A 14" wheel need a matching lug nut pattern and clearance for the brake. The 14" wheel on our 03 has four lug bolts and the 15" on our 10 has 5 lug nuts. But you raise something I've been thinking about . . . the donut spares.

I've thought about putting four donut spares on either car just to 'have fun' on a marathon drive.

Bob Wilson

 

Would this be for a phantom MPG boost?

 

Spoofing is too easy and boring. The hard part is getting the other drivers properly attired:

• I Think We're all Bozos on This Bus - Firesign Theater

Bob Wilson