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Old 05-08-2014, 02:52 AM   #21 (permalink)
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Originally Posted by NachtRitter View Post
Puzzled by this... isn't that what the EPA sticker on the car tells you? What the FE of the car is based on a set of common tests (applied equally to all cars) as specified by the EPA?
Yup.

A common set of tests that is either woefully pessimistic (for us) or woefully unrealistic (for people on the other end of the bell curve).

The problem is, EPA auditing is spotty enough that a lot of cars slip through the cracks with numbers that are not comparable to other cars on the same driving cycle. Per-variant testing is expensive, but it's probably time the EPA (or some independent third-party) took over testing duties from the manufacturers.

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Old 05-08-2014, 04:09 AM   #22 (permalink)
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I prefer to err on the side of freedom of speech and caveat emptor. Besides, all of the misleading fuel economy figures the marketers are trumpeting are canceled out by the knuckle-dragging troglodytes from Consumer Reports and Car & Driver that claim far below EPA figures for the vehicle.
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Old 05-08-2014, 12:23 PM   #23 (permalink)
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Quote:
Originally Posted by niky View Post
Yup.

A common set of tests that is either woefully pessimistic (for us) or woefully unrealistic (for people on the other end of the bell curve).

The problem is, EPA auditing is spotty enough that a lot of cars slip through the cracks with numbers that are not comparable to other cars on the same driving cycle. Per-variant testing is expensive, but it's probably time the EPA (or some independent third-party) took over testing duties from the manufacturers.
I agree it's not perfect, and I have no doubt that manufacturers try to game the system especially since money's on the line. However, since the test procedures are publicly available, it is possible for others (outside of the manufacturer or EPA) to "sanity check" the manufacturer's results. That's a benefit of having quantitative testing. And if the test results fall outside a reasonable range, then there is a way to challenge the manufacturer's results with the EPA (as was done with Hyundai back in 2012).
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Old 05-08-2014, 03:29 PM   #24 (permalink)
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I think the MPG data should be presented as a series of 4-curves, with MPG on the Y-axis and MPH on the X-axis. In descending order, the curves would be:

1) MPG vs MPH with driver only, no A/C
2) MPG vs MPH with driver only, A/C operating
3) MPG vs MPH with driver, max. passenger(s)/load, no A/C
4) MPG vs MPH with driver, max. passenger(s)/load, A/C operating.

Initially, the data would come from actual, on-the-road vehicle tests, but as soon as the preliminary data was collected and analyzed, computer-simulations would be sufficiently accurate enough to eliminate further road-tests...until something aerodynamically or mechanically on the subject vehicle was changed.
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Old 05-08-2014, 03:39 PM   #25 (permalink)
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Unfortunately, that's not likely to make a difference... Too much information for the average consumer, and still gives the manufacturer options to tweak the numbers ("Of course a 50lb driver is realistic!"). Probably the best approach is for the consumer to understand that "their mileage may vary" from the posted value (if he/she even cares about that).
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Old 05-08-2014, 04:36 PM   #26 (permalink)
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Maybe the rating should be split into 3 categories, reflecting driving style.
Some cars, especially hybrids with an automatic gearbox, compensate somewhat for bad driving style as they regain some of the energy wasted on excessive braking and such.
Other cars, like the tiny turbo ecodiesels, start using loads of fuel when revved.

We need not one but 3 combined ratings; one when driven spiritedly, one when driven averagely and one when driven eco conscious, let's call that the CAH rating.

My car (41 MPG EPA combined rating) may have a CAH rating of 33/41/55 MPG.
My colleagues Skoda Fabia 1.2 TDI would have a CAH rating of 30/45/70 MPG or something like that.
So if you are foot heavy you'd know the Fabia would not save you anything compared to the Insight, while if you hypermile you'd save a lot.

Btw. CAH stands for Clarkson/Average/Hypermiler. Other acronyms are still possible at this stage
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Old 05-08-2014, 07:38 PM   #27 (permalink)
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Even that isn't enough to get more accuracy. Flatland vs mountainous, urban vs rural, windy vs calm, and altitude and humidity are going to have impacts too. Might have to add, does a train cross in front of the motorist at any point, and for how long, and is that period going to be engine on or off?

How in the hell can any test regimen take into account all the variables and give everybody dead-nuts accurate numbers? Should the consumer have to fill out a questionnaire- providing inputs for variables for their specific conditions- before they are granted access to any mpg estimates? Key word being ESTIMATES. Is the test supposed to provide every individual motorist with the exact average mpg they actually get, or is it supposed to provide the consumer comparative information between models?

I don't see the problem with the current system. You look at the number, you consider your own circumstances, you adjust your expectations accordingly.
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Old 05-08-2014, 10:33 PM   #28 (permalink)
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Well, if EPA can't provide more accurate numbers, maybe they should "require" smarter buyers (wink,wink)!
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Old 05-08-2014, 11:07 PM   #29 (permalink)
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Quote:
Originally Posted by Frank Lee View Post
Baloney! 1st gen EPA were darned high and virtually unobtainable by non-hypermilers. 2nd gen EPA was easily obtainable by simply driving sensibly. 3rd gen EPA has been dumbed down to reward idiotic driving. Anyone that can't get EPA now ain't doing it right.
I've only gotten under EPA HIGHWAY mpg with my Mustang ONCE. And I had to do a few things wrong to achieve that. YMMV
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The presence of traffic is the single most complicating factor of hypermiling. I know what I'm going to do, it's contending with whatever the hell all these other people are going to do that makes things hard.
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Old 05-08-2014, 11:11 PM   #30 (permalink)
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I would have to agree with most of you when speaking about the chevy cruze. No I do not have the cruze diesel unfortunately . But I was most frustrated by the window sticker claiming I would get 42 mpg highway and that I do but only when the highway is flat seamless road. I fight to get above 42 mpg on my 26 mile commute to and from work..
My cobalt which is just a old generic looking cruze has an average of about 47mpg over the lifetime of ownership. It gets the best fuel economy at steady speeds well below the 65mph limit.

My guess is that you live in a cold state, you have an automatic and you must not have the best hypermiling ability.

Unless of coarse you have a mix of in town and highway, then getting 42mpg is actually impressive, since any city is going to drop you real fast due to the low rating in the city.

Now if you had a manual transmission, I would say there is something wrong.

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