Driven5
UltraDork
9/4/19 10:11 a.m.
If it didn't matter, then manufacturers wouldn't risk cheating it. If it wasn't for our society's fixation on fuel economy, we wouldn't be able to enjoy the unprecedented combination of fuel economy and performance that we have today.
Knurled. said:
freetors said:
In the latest investigation, the EPA confirmed software in VW cars was shifting gears inappropriately (to achieve optimal fuel economy) during the lab tests used to estimate fuel efficiency. The cars and SUVs wouldn’t make the same kinds of gear shifts in the real world, which means consumers were actually getting lower gas mileage
Huh... I thought basically all the manufacturers were trying to game the EPA ratings tests to the detriment of real world economy. For instance the whole wave of small displacement turbo cars.
That depends. The small displacement (1.9l) turbo car I used to own would get a real world 37-40mpg highway no problem. The small displacement (2.5 is small for a 4000lb AWD hosebeast) turbo car I currently own will get a real world 27mpg highway no problem.
...And my naturally aspirated V6 pulls a 4500 pound house on wheels, but still also manages similar highway fuel economy as your substantially smaller and sleeker car.
It's not that small turbo engines don't get good fuel economy. Rather that the EPA test cycle seems to often favor reduced displacement turbo engines over similar performance naturally aspirated engines in such a way that the turbo engines do not provide the same real world fuel economy advantage over a similar naturally aspirated engine as their EPA ratings would indicate on paper. Basically this appears to be a contributing factor for (at least somewhat) artificially driven the manufacturers to favor building and (overly) marketing these reduced displacement turbo engines, and has led to what I believe is a largely ingrained misconception with the car buying public. But this is why it has always amused me in comparison tests when the 'lowest rated' naturally aspirated cars would often equal or best the smaller displacement turbo cars for 'as-tested' fuel economy.
In much the same way, the EPA ratings seem to often disfavor diesel engines relative to naturally aspirated gas engines, such that they often do even larger advantage in the real world than their EPA ratings would indicate on paper.
In reply to Driven5 :
Not sure how you came to the conclusion that the cycle favors small turbos vs. nominal NA engines. If that were the case, Toyota would not have found the 2.5l that I've been raving about for a couple of years now. The real reason that small turbos are used now is internal company politics- but that's a totally different discussion. The cycle has really nothing to do with it. I've seen plenty of data about that. Especially now that the sticker FE number has both the US06 and the SC03 incorporated into it.
And I very much don't see the diesel part- they clearly get better FE on the cycle just like the real world. Diesel's problem is that they are judged equally to gas WRT the rest of the emissions- and in that area, they totally fail- both in cost and ability to be as clean as gas engines. And that applies even more to the real world driving.
Hoondavan said:
My Alltrack's computer is consistently 2 mpg optimistic, apparently they are all. My real-time mileage (mostly highway) does typically exceed the EPA estimates.
That's the thing that astounds me about the S60. I generally reset the trip odometer and fuel economy average at every refill. When I multiply the fuel refill by the reported fuel economy, the answer is within a tenth of a mile to what the trip odometer would read.
The S40 was only accurate if I never stopped, which is only practical on long trips. And, as an aside, the distance to empty was horrendously inaccurate - the tank was maaaybe 11 gallons if you ran it dry, but the computer assumed a 16 or 18 gallon tank. No idea how they stuffed that up.
Years ago I had a car that got 27 mpg on a road trip. I was happy.
Today I can get 35 mpg on the same trip. So I am still happy.
That is 2 mpg better than than rated. I'm still smiling.
In reply to alfadriver :
I wouldn't go so far as to say it's a 'conclusion', but more of a hypothesis supported by numerous test results and data point clouds...A theory, if you will.
For example, there is a substantial body of data supporting the 5.0 F150 typically equaling or besting the 3.5TT F150 for real world fuel economy, and little (none?) supporting the 3.5TT having any of the rated advantage in the real world. The current F150 4x4 3.5TT is rated for 12.5% better fuel economy than the same with the 5.0. Honestly, I'd love to see the real world data tending to support this...But as of yet, I personally have not.
Regarding Toyota, even if there is a legitimate disparity between lab testing results and real world results, that in no way, shape, or form prevents somebody from simply building a better mousetrap. If my competition used a technology that gave them a bigger competitive advantage on paper (marketing) than the real world, but I figured out a way to improve my current lower cost (higher profit) to produce technology to ensure that not only equal or best them in the real world, but equal or best them on paper as well...Why wouldn't follow that path, even if it means not following the crowd?
In reply to Driven5 :
When I go to Fuel Economy dot gov's site, for 2019, it shows the same 5.0l F150 and a 3.5l Turbo F140 have the same sticker fuel economy. Actually, 10 speed auto, the 5.0l is rated at 1 MPG better on the highway. I see that there are a lot of other configurations available, especially in terms of options for the 5.0l that lower it's FE- but for a basic 2WD truck with normal (not LT tires) they are exactly the same. https://www.fueleconomy.gov/feg/Find.do?action=sbs&id=41023&id=41026
It's not until you get to the high GVWR where the turbo starts getting a test advantage. And the difference there is ~6% rated. Not 12.
The reason I go to that page- all of that data is calculated via the testing. So as I see it, they come out the same.
I've seen plenty of tests, and turbos don't really have an actual FE test advantage...
Still, as a measure where consumers can measure one car to another, it's the best we have right now. The future is going to be different- with actual real world testing- so I'm not sure how FE is going to be compared when the tests are outside of a lab.
In reply to alfadriver :
My local dealership has 139 4wd and 11 2wd trucks. Even accounting for regional variation, I'd argue that choosing 4wd is far more representative of the real world: Yes 12.5% was comparing the higher GVWR 4wd trucks, and admittedly I don't know how likely it is to be optioned one way or the other in that regard. But even if most of those 4wd trucks are actually in the lower GVWR range, as you noted there is still a measured and advertised/marketed/perceived advantage where one does not seem to generally exist in practice.
And it's not just F150's either. It's a trend that has appeared across numerous makes/models, be it more directly comparable within a single model, or more indirectly between competing models.
Even if the total error is relatively small, if companies are willing to risk cheating the system over 1 mpg, it's obviously important enough to sway decision makers. I do agree that it's the best we have right now, but that also highlights a lack of alternatives. Since it seems to appear with surprising consistency, it indicates to me that the test likely has an inherent bias. While not a trivial task, it should certainly not be insurmountable to improve the test to more accurately reflect relative real world results and better level the playing field between all of the competing (and complementing) technologies...Not just naturally aspirated vs turbo. In my humble opinion, it's time for them to go back and finish what they started in 2008.
In reply to Driven5 :
I have not much experience with either, but my employer's brother has a 2.7 Ecoboost with 4wd and all the stuff. When I serviced it, his fuel economy minder was showing a bit over 19mpg average.
Even accounting for optimism, that's really good for a 6000lb truck.
Cooter
UltraDork
9/4/19 3:55 p.m.
I think the key here is that it isn't like Smoky Yunick placing a basketball in a fuel tank to increase capacity beyond what NASCAR said was legal to gain an advantage.
This was a corporation defrauding the US government, as well as the American people.
Fuel economy is important to us. We drive a lot. That's why we have the truck we have and the wife's Forte (which we've recently learned LOVES shell gas). Honestly I don't care what the epa ratings are anymore, I haven't had a vehicle that won't smash them with our driving. I mean, Iwas getting 18mpg daily in a 5500lb truck in stop and go driving every day.
In reply to Driven5 :
Even with the different models and configurations, equal packages are no more than 1mpg different. Which is just over 5%. I would not call that some kind of cheater based on that- especially since the numbers are whole numbers.
Any noted bias is regularly complained about by consumers. VW is not the only one that have been penalized for incorrect sticker numbers- we have been multiple times. And having an optimistic number that doesn't match also means unhappy customers, and I've seen those reports, too.
While not perfect, I really don't see the turbo bias in the testing.
Snrub
HalfDork
9/4/19 5:28 p.m.
Regarding the turbo vs. n/a fuel economy numbers. I believe for earlier downsized turbo engines, some were good at obtaining EPA numbers, but not real world numbers. Last year C&D took their measured fuel economy, data from another source and compared it to EPA data. They found significant discrepancies, both positive and negative for both turbo and n/a engines, but they actually found that on average the fuel economy of turbo engines was slightly better than the EPA numbers, while n/a engines slightly missed the EPA values. https://www.caranddriver.com/features/a20776954/are-turbocharged-engines-a-fuel-economy-boost-or-a-fuel-economy-bust/
They also did a specific comparison of the F150 5.0L vs. 3.5 ecoboost: https://www.caranddriver.com/reviews/comparison-test/a15100999/2016-ford-f-150-lariat-50l-v-8-4wd-vs-2016-ford-f-150-lariat-35l-ecoboost-4wd-comparison-test/
Driven5 said:
Knurled. said:
That depends. The small displacement (1.9l) turbo car I used to own would get a real world 37-40mpg highway no problem. The small displacement (2.5 is small for a 4000lb AWD hosebeast) turbo car I currently own will get a real world 27mpg highway no problem.
...And my naturally aspirated V6 pulls a 4500 pound house on wheels, but still also manages similar highway fuel economy as your substantially smaller and sleeker car.
While true, my "smaller and sleeker" car is biased to performance, not cruise economy. If it had a high compression engine with a low pressure turbo, or a modern relatively very high compression DI engine with a moderate pressure turbo, I'm sure the economy would be way better. (Another reason I am looking forward to the RS3 that I am all but convinced is going to eventually replace it)
As it is, I'm thrilled to have something that can run 13s, carry me around in luxury, tow my things, defy physics on a regular basis, get up to 30mpg highway if I feed it 87 (only in flatlands though, because I have mechanical sympathy), and look like some boring sedan.
Which reminds me, yesterday I learned that there was a 1st gen LaCrosse (or whatever the midsize Buick was) with the 3.6. 280hp, not to far off from the 303hp 5.3l. Very interesting.
In reply to Snrub :
Thanks. Interesting read, and a good counterpoint to other observations. While the F150 test went exactly as expected, I think that the more widespread test might just be the first solid (publicly available) data set I've seen that supports alfadriver's statements. Being that it's still basically a singularly uniform 'laboratory' type test, I'm not going so far as to say it single handedly discredits contrary observed tends. But maybe, just maybe, that guy actually does know a thing or two about this stuff after all.
Just a point of reference: In the early days of EPA ratings, Dodge Dart Lites and Plymouth Feather Dusters were rated at 36/24 MPG (225 Slant six, stick and tall gears, some aluminum parts, etc.). They gamed it well.
In reply to slantvaliant :
Be interesting if they'd dusted off the molds from the early 60s for casting aluminum blocks.
Heh... dusted