Real World MPG Numbers

Now that a few of us have a 2016 Prius is the mpg dash gauge accurate or does it over state mpg just like all the 2010-2015 Prius are noted for. Our last fillup in our 2010 was off by 3.2 mpg nearly 7% off. Its been always off since new with over 137,000 miles.

 

OK, I think I understand.

Since the Model 3, Model 3 Touring, Model 4 and Model 4 Touring are considered "the same car", Toyota only needs to have mileage certified for one of them -- just so long as they all weigh pretty much the same. That might explain why you can't get the 4 Touring with a Moon Roof and/or Full Size Spare Tire. Because if the 4 Touring could have those features, then its weight would be different enough from the others that it might need to get its own certification.

Do I understand the logic correctly?

That kind of makes sense for options that don't have a material impact on MPG (the addition of fog lights, carpets, lumbar supports, dimming mirrors, etc ...) but if the tires/wheels are known to have a material impact on MPG, it does not make sense at all !!!!!

I would have PROBABLY gone with the 4 Touring and its 17" tires even at the expense of (likely, as per Prius Chat wisdom) lower MPG, but to be frank I feel rather cheated that Toyota represented is mileage as equivalent to everything but the Eco.

Shame on them, really.

Of course the actual MPG delta will determine the degree of my pissed-off-edness.

 

MPG is a personal, individual and car, thing. All the EPA can do is provide a standard set of tests to give a relative metric between different cars. There are no MPG guarantees.

Bob Wilson

 

Understood, but reports here on Prius Chat suggest that the mileage difference between a Prius with 15" tires and one with 17" tires is significant-- even thought Toyota represents them to be identical.

That may be legal, but if it's true it is also very sneaky.

 

@krmcg

Trying to see the scenario that would have displayed and calculated mpg close on the first fillup, then divergent by around 7% on the second: it could be they filled it on the neck when they delivered it to you (commendable, I guess), so when you refilled just till the first shut-off, the calculated mpg improves. But on the next tank, again stopping when at first shut-off, since you're doing the same as the previous tank, the calculation is more realistic.

Are you THE 2016 Prius on Fuelly? Seems like they're still setting it up: just for laughs I tried adding one but it would allow me to.

Again, disgustingly good mpg you're getting!

 

@ krmcg
keeps posting like this, then we will see trend after a few more fill up? I got a question, is the filler neck on the gas tank same size as the Gen 3 compared to Gen 4?? If I tried to fill up to first click on the gen 3, I would never get 10 gallons of gas in. My fill ups will hold an additional 1-2 gallons more after first click. Another factor is how fast the gas is going in and backs up in neck to turn pump off. Time will tell unless there is someone out there that has filled to the neck and calculated a tank already. This is referring to the accuracy of the dash fuel gauge.

 

Yes, knew you went from a gen 2, does the gen 4 seem about the same as gen 2 in refueling. It was a little bit of a problem on the gen 3, I didn't like how slow they filled was hoping that would be corrected.

 

This is a hard problem to diagnose from a discussion group.

I took a quick look at two Michelin tires, same model, 15" and 17" and found only a 1.4% difference in revolutions per mile. That also goes along with my study of how the brake controller had no adjustment for different wheel or tire sizes. So the remaining hypothesis are:

• wider - might increase the aerodynamic drag
• tread depth - might change rolling resistance
• shorter sidewall - might flex more increasing rolling resistance

These are all credible hypothesis but without a pair of 17" wheels and tires to test, there is nothing I can backup with hard data. So I caution about making a claim about 'Toyota represents them to be identical' unless there is hard, engineering data to back it up. Let me give an example.

Last year some were claiming that the brake safety patch caused the mileage of the Gen-3 to go down. Now when we took delivery in May 2009, the first thing I did was a set of benchmarks to know what our car did 'off the lot.' I went back and replicated a data point under 40 mph and over 55 mph and they were identical to the original benchmark. So I could not verify that claim but one user insisted the patch was the problem and all but refused to replicate my benchmark protocol.

He complained often and long enough that the regional support team came down and took his car for a drive with him in it. They easily busted through 50 MPG. He had the character to share the results with PriusChat.

I will support any credible complaint about our Prius IF I can replicate it. But if I can't, I'll offer some suggestions on how to diagnose what is going on but I won't join a 'rumor mob.' It is not in my nature.

Bob Wilson

 

You got it. The EPA simply doesn't require different tests for different tires, but I was a little surprised Toyota didn't test separately after having done so with the Camry hybrids.

 

Toyota marketing materials could not be clearer: the MPGs touted for the 4 Touring (which is only available with 17" tires) are IDENTICAL to the 4 (which is only available with 15" tires).

No caution needed: Toyota makes that claim without qualification (Edit: they do say they are coming from the EPA in footnote, I suppose that is a qualification if you are splitting hairs).

Based on that claim (in part) I elected to make a purchase the 4 Touring. There are only two possibilities, the claim is true or it isn't.

Actually there is a third possiblity: Toyota's claim by way of the EPA that my model gets the same mileage as the one with 15 inch tires is legally true under the rules of the game, but not true at the pump.

The collective Prius Chat wisdom across many model years suggeat the third possibility cannot be discounted.

I love my car, but think I may have been snookered.

 

as a member here for 5 years, i'm surprised you missed this on the gen 3. the good news is, you can sell your 17's and put on 15's.

 

The calculated mileage could be inaccurate due to error on the gas station pump. Several years age I did a test that showed I was not getting a full gallon of gas when the pump said one gallon. The government responsible for testing accuracy of gas pumps said they only had enough staff to check a station every few years.

 

Toyota chose to test the best one (ECO version) and an "average" one, what more do you wan't? Different MPG for every package? We don't know if this average model is on 15" or 17" wheels, but from first results on road we can assume that Toyota left us more margin than with Gen 3.

 

I certainly didn't thinks so, but after reading posts on the MPG impact of different tire sizes for the 3rd Generation, yes. Absolutely.

At least when it comes for tire size.

I am thinking the "average model" approach is no different here than if a hypothetical manufacturer used a testing vehicle with LRR tires to get a good MPG certification attached to their models with run flat / high performance rubber.

I like.to think I am pretty savy , but having not spent much time on Prius Chat over the past few years the potential MPG hit of the choice I made 2 weeks ago took me by surprise.

Moving forward in this thread, I will stop beating this horse (at least for a while) and post my MPGs later today -- after my 3rd fill up.

They will be in the low 50s, I think. Any delta with others' results will flow from many factors of course.

 

Fill ups -- 2016 4 Touring

1/28 -- 500 miles on odometer -- 9.3 gallons -- 53.7 mpg for tank
2/2 -- 1001 miles on odometer -- 9.7 gallons -- 51.6 mpg for tank
2/9 -- 1441 miles on odometer -- 9.4 gallons -- 46.8 mpg for tank

1441 miles to date 49.1 mpg on display

 

If I done this right then the hand calculation would be 50.7 mpg, correct me if I'm wrong