Hyndai's and Kia's being dinged for fudging MPG's why not Toyota?

It also depend on where you live. Up here in the northwest we get 7-9 months of rain a year.
Which means defrost, windshield wipers on, headlights etc, and wet roads, temps in the
40's. Last fill up was 48 mpg calculated, before that 45 mpg calculated. Lets not forget winter blend fuel with the
negative effect of 10% Ethanol. 50 mpg calculated is nearly impossible in these
conditions.

Summer months 52-54 mpg calculated......

 

You would think, but:

In my experience with a second generation Honda Civic (corraboratd by MSantos, for one*), the in-dash display of mpg (or liters / 100 km) consistantly underestimated fuel efficiency. Not by a lot, it's close to spot-in, but typically a bit pessimistic. So when you calculate, you might go from 5.0 (liters per 100 km) to 4.9.

That's about the only positive I can say about the HCHII right now, though, LOL.

They've got mpg display in other vehicles as well, one that I know of is the Honda Pilot (pretty depressing display though). My guess is they would have similar accuracy, but I've never checked.

* BTW, where the heck is MSantos?

 

My friend tells me his 2005 Mustang GT, and 2012 F150 EcoBoost MPG readings are spot on. Too bad they always read in the high teens and low 20s.

 

the accuracy of the fuel flow meters might not be suitable for 40+ mpg applications.

 

I can understand if they have a precision problem at the high end. But an accuracy problem, is easily remedied, if they want that is, with and offset.

If they apply -5% to the number, I bet the distribution will center on the calculated numbers.

 

A risky move by the Koreans. They've gained many buyers for their cars based on their fictitious mileage claims. All it cost them was a couple hundred dollars per auto in their gas debit cards. A fraction of a new car price. I can imagine a good amount of 2011-2012 Hyundai Elantra owners purchased the car based on its 40mpg hwy rating.

Now the fallout.....

 

I'd imagine it's based on injector timing and not fuel flow. Problem is, I can the see potential for a lot of errors to add up and to be further magnified by how crappy floating point arithmetic on computers can be. Hence, I'd imagine automakers have to do some calibrations/adjustments before going into production. Even then, they don't necessarily get it right.

IIRC, my former 02 Nissan Maxima's trip computer was usually 1-3 mpg off, sometimes more like 2-4 mpg off. That's pretty big when I was getting no better than 24 or 25 mpg, at best, and a LOT worse w/short city city drives. My former 04 350Z's trip computer was better. It was usually 0-1 mpg off, usually no more than 0.5 mpg off.

 

The Elantra GLS autobox easily exceeds the window sticker mpg's. It even comes real close to the Prius on the highway calculation. City driving was ~32 mpg if I remember correctly. I did a 2400 or so mile test drive last summer in a 2011 Elantra GLS. My results are posted on this forum. I also drove a few Sonata's thousands of miles. Even the Sonata can easily exceed the window sticker mpg figures and none of that was driving it slow to make the numbers higher. Being that both are gasser cars, there is a big difference in mpg numbers driving them normal or driving them like you stole them. Lots of good stories on the Hyundai forums They both are very nice cars.

Mike

 

They are not accused of building bad cars, they are accused of not following EPA test procedures.

 

Here's my remedy (simplistic as it is): The Prius's computer caculates the MPG as it already does, and before it sends the information to the screen, it subtracts 2 MPG (or whatever amount the tests find the computer to be off, or even a percentage). I'm good with whatever number comes up. I only take the computer's number as an estimate. I don't lose sleep that it is about 2 MPG off.

Alternatively, the user is allowed to program the number that will be subtracted (or even added) based on the user's own calculation. This might be more expensive, but at least the program really doesn't have to be changed much.

And if it helps the conversation, I think there is no requirement for the accuracy of the MPG reading because it doesn't affect the reality of the MPG, only what we read. But I think Toyota should try to make it more accurate, if it can. Plus, Toyota isn't making a representation as to its accuracy. But when stating MPG, it is representing that it followed the EPA guidelines (right?).

Mike

 

Hyundai got caught cheating on the rules, hence the fine. Toyota puts software in their computer to lie to us to tell us we are getting higher mpg than we are, but they are doing it within the boundries of the law. Hence no fine, unless they are doing something we don't know about.

Here you go, how the vehicles are tested
Detailed Test Information

The epa typically only tests one car from a line. They depend on toyota to follow the rules for the 5 trim. A manufacturer is allowed to average its test results by projected sales on similar trims. We don't know exactly what toyota got on internal testing of the 5 trim, but they said it was 5% worse (arround 2 mpg) in the past. Since they sell many more of the other trims this likely does not affect their sticker.

Has someone done comparisons on the same roads etc with the 15" or other 17" compared to the OEM. I had not seen that but I haven't followed all the links.

btw: my average is around 42mpg mainly because of warm up penalty and hills. This week I took different routes, slower routes with more traffic and lights. The computer is reading 52 - likely 50 mpg, but its definitely not worth the traffic frustration. YMMV and those greatly exceeding epa have an easier driving profile than they do. Most of us do not, but we don't post on fuelly either.

 

That would be good, but it is likely toyota marketing is giving us inaccurate readings on purpose. Unless they are shamed into fixing it they won't. They are withing the error allowed by law, and I really don't think we need to add more laws, just expose the company that is lying to us.

 

I have not seen any serious controlled tests other than the questionable UK test. However, I've done a ton of testing with various 15" tires (OE and aftermarket) and 17" tires (aftermarket only) and depending on how much one hypermiles he hit can be quite large. I wish I could test a set of the OE 17s because I have a feeling they are very fuel efficient compared to most of the aftermarket 17s. This is possibly how Toyota can stay within the EPA rules with the Five. Those who have switched from the OE 17 to an aftermarket 17 observe a big drop in FE even when using a so-called LRR tire. The general consensus is the average person losses 4+mpg when going from the OE 15s to a 17" tire. The loss is exacerbated when going from a superior LRR tire like the Energy Saver A/S to a 17" tire. I was seeing a 6-8mpg loss switching between such tires.

I've had this GenIII since March but I've already tested three 15" tires and four 17" tires.

 

Just curious, if you have a thread on that already post a link. Otherwise what were your results with each tire and the OEM.

 

So we're moaning that Toyota's mpg display is 5% out. But we only actually notice that because it their cars are so economical.

5% out on 12 mpg is not going to show. 5% error on 60 mpg will.

This is a non story.

 

Grumpy, if we can't whine about the little things then we don't have anything to whine about.

I'm not about to whine that I don't have anything to whine about.

 

Here are a couple.

Installed Lexus CT200h 17" wheels and 205/50/17 tires | PriusChat

Testing MPG with 17s vs. 15s | PriusChat

 

+1

Thanks. I'll buy the 2-4 mpg hit on 17" wheels/tires versus stock. I found it interesting that you found a 15" so much better than stock. I can see if you found that magic on the OEMs how it would boost mpg.

I only drive the prius about 13K miles a year, much of it on short fast trips which hurts my mpg.

I pulled up the toyo's that tire rack says are toyota OEM, but they don't even get labeled LRR.

 

Within a certain range, they are allowed to lump the various configurations together and report the average result of the entire lot. Several PC members who were invited to the introduction events back in early 2009, and meet with the Prius engineers, were shown a page of Toyota's preliminary internal EPA figures for the different configurations, and even posted a photo of it. The V (now Five) clearly had lower numbers, and that was averaged into the final figure for the whole line.

The PC consensus was that the V did not get a sunroof option because the added weight would have either (1) pushed it out of the bounds that allowed it to be lumped in with the other configurations, or (2) pushed the whole Gen3 line average down slightly, below the rounding threshold for 50 MPG. "49 MPG" just doesn't carry the same marketing weight.

 

The hit is very consistent. I observe this "big" drop whenever I put a set of 17s on despite running LRR tires. I even had a light weight set of 17s and the hit was still there and about the same vs. my new much heavier wheels (15lbs vs. 24lbs).

Most passenger cars come with a LRR tires from the factory in an attempt for manufacturers to meet CAFE standards. The tire when available aftermarket sometimes isn't labeled as LRR but it's a pretty good bet they are. I confirmed this with CapriRacer, a well known tire engineer, on other forums and personal communication. In the case of the OE Toyo 17" tire I think Toyota focused heavily on making that tire super fuel efficient which detracts from the tire's ride quality, longevity and traction. Most tire manufacturers wouldn't do something like that for a 17" tire since they are considered more of a performance sized tire historically. Now that more non-performance cars are coming equipped with 17" tires that will likely change. This is just my opinion of course.

The OE 15" is pretty fuel efficient compared to most aftermarket tires but there are more efficient tires out there. As illustrated by TireRack's test "When Round and Black Becomes Lean and Green", fuel efficiency in a tire varies by model. I too was surprised by how good the Energy Saver A/S was compared to the OE tire. Anecdotal information posted by members who track their mpg meticulously has backed this up. Unfortunately, we have not found anything more efficient in a 17" size than the Toyo Proxes A20. My money is on the Ecopia EP422 and PureContact with EcoPlus for now. I wish the Energy Saver A/S came in a useable 17" size. I liked that tire.

Tire Test Results : When Round and Black Becomes Lean and Green