How much fuel does ASS (Auto Start Stop) save?

[DaltonGang]

I love reading about how forcing ESS(ASS) on society is a good thing, from certain members. All in the name of bettering the environment. All the while, these members are driving Wranglers, which are notoriously fuel inefficient. TOTAL HYPOCRISY!!!!! Also, a lot of Righteous Indignation being thrown about.

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[Fatbob Frank]

Total props for the use of "Righteous Indignation"...

 

[Ratbert]

The link is in post #107.

The 26.4%/20.8% difference is just the way percentages work calculating ASS-less up or ASS down. Over 1.18 miles in about 10 minutes, the Ford Ranger got 14.9 mpg on ASS and 11.8 mpg ASS-less, a difference of 3.1 mpgs (the actual fuel difference was 0.018 gallons).

Ok, I finally did my due diligence and read the study itself instead of just the outline. I stupidly thought that link was to the same summary.

How is it, in your opinion, a crap study? No set of testing will cover all possible scenarios due to budgetary constraints, but in what way was it crap?

 

[THAW]

How is it, in your opinion, a crap study? No set of testing will cover all possible scenarios due to budgetary constraints, but in what way was it crap?

I mentioned a couple reasons in post #115.

I'll add a nit-pick: projecting fuel consumption to gallons per 100 miles (2 orders of magnitude for some tests) instead of using raw data in the tables is misleading since it's unlikely ASS function is sustainable at included rates over that distance, and the percentage breakdown already serves the same normalization purpose.

The document is clearly worded/summarized and cited to promote ASS, rather than designed to be a scientific study of anything - certainly not real-world benefit. Realistically, the (small) data set points more toward how much ASS can game EPA mileage tests than it proves how beneficial ASS is to consumers and/or the environment. But like I wrote earlier in the thread, it's an interesting experiment nonetheless.

 

[Ratbert]

I mentioned a couple reasons in post #115.

I'll add a nit-pick: projecting fuel consumption to gallons per 100 miles (2 orders of magnitude for some tests) instead of using raw data in the tables is misleading since it's unlikely ASS function is sustainable at included rates over that distance, and the percentage breakdown already serves the same normalization purpose.

I'm not sure what you mean by "instead of using raw data in the tables". Comparing MPGs isn't really valid since it isn't a linear measure, therefore making it significantly harder to compare how much fuel / money is saved when moving from lower to higher MPGs.

For example: going from 10 MPG to 20 MPG (100% increase) saves 5 gallons per 100 miles. Going from 30 MPG to 40 MPG (33.33% increase) saves a mere 0.83 gallons per 100 miles.

Gallons per 100 miles is linear. That is, there's a direct correlation between the numbers and percentage of delta.

There's no way we'd ever convert to that system (or hell, the metric system), but many people (sometimes myself included) tend to compare two MPGs and think they know what percentage change is indicated as it relates to how far you can travel.

Sorry if I went off base and you were actually talking about something else in regards to raw data.

 

[NWJeepr]

Just because you don't "like" the study or its result doesn't mean it isn't a valid study.

But that's the shit society we live in. Don't like the answer? Shop until you find one you do like, even if you're wrong.

 

[THAW]

Just because you don't "like" the study or its result doesn't mean it isn't a valid study.

But that's the shit society we live in. Don't like the answer? Shop until you find one you do like, even if you're wrong.

Anyone who believes ASS improves fuel economy by 20-25% certainly shopped for his answer (and likely didn't read the "study" that provided it - perhaps even believing a conspiracy about politicians hiding it).

 

[THAW]

I'm not sure what you mean by "instead of using raw data in the tables". Comparing MPGs isn't really valid since it isn't a linear measure, therefore making it significantly harder to compare how much fuel / money is saved when moving from lower to higher MPGs.

For example: going from 10 MPG to 20 MPG (100% increase) saves 5 gallons per 100 miles. Going from 30 MPG to 40 MPG (33.33% increase) saves a mere 0.83 gallons per 100 miles.

Gallons per 100 miles is linear. That is, there's a direct correlation between the numbers and percentage of delta.

There's no way we'd ever convert to that system (or hell, the metric system), but many people (sometimes myself included) tend to compare two MPGs and think they know what percentage change is indicated as it relates to how far you can travel.

Sorry if I went off base and you were actually talking about something else in regards to raw data.

Ya, including both MPGs and actual fuel consumption makes sense.

I meant converting fuel consumption to the 100-mile equivalent instead of printing actual fuel use in gallons/ounces/whatever. To me, it's disingenuous to imply 1.18-mile ASS findings will hold up over 100 miles since ASS will almost certainly be automatically disabled by a vehicle driven under the test conditions for that distance.

Bottom line is, it's obvious ASS doesn't improve vehicle fuel economy by 20-25% except to the extent data is highly cherry-picked. It's not possible for car batteries to indefinitely support discharge rates from vehicle electronics/accessories for 38% of operating time plus restarts while being charged at a much lower rate by the alternator during the other 62% of operating time.

 

[NWJeepr]

Anyone who believes ASS improves fuel economy by 20-25% certainly shopped for his answer (and likely didn't read the "study" that provided it - perhaps even believing a conspiracy about politicians hiding it).

It's not the only study to be done on it. It has the potential to save fuel...I'm not sure why this is a subject of debate other than you don't like the fact that the technology became commonplace and had monetary incentives provided by the government to automakers for using it.

 

[Jtphoto]

An interesting observation.. if you leave your eco screen up and watch your mileage around town. Even within a few hours of ASS on and then An hour with ASS off, I have seen it register a difference.

 

[THAW]

It's not the only study to be done on it. It has the potential to save fuel...I'm not sure why this is a subject of debate other than you don't like the fact that the technology became commonplace and had monetary incentives provided by the government to automakers for using it.

My liking or not liking ASS has no bearing on the quality of the experiment (which should not be referred to as a "study" as though it was conducted scientifically and peer-reviewed).

Studies have been done, yet somehow in this thread we've only gotten multiple, independent references to the same crap experiment and its 20%/25% headline number.

 

[NWJeepr]

My liking or not liking ASS has no bearing on the quality of the experiment (which should not be referred to as a "study" as though it was conducted scientifically and peer-reviewed).

Studies have been done, yet somehow in this thread we've only gotten multiple, independent references to the same crap experiment and its 20%/25% headline number.

So, search for some more. Prove it wrong.

 

[Ratbert]

My liking or not liking ASS has no bearing on the quality of the experiment (which should not be referred to as a "study" as though it was conducted scientifically and peer-reviewed).

Studies have been done, yet somehow in this thread we've only gotten multiple, independent references to the same crap experiment and its 20%/25% headline number.

There's always the test in the original post that found it saved 4 to 8.7% in the scenarios tested. Definitely not as laboratory-based as the "crap" SAE tests though.

 

[THAW]

There's always the test in the original post that found it saved 4 to 8.7% in the scenarios tested. Definitely not as laboratory-based as the "crap" SAE tests though.

I think the EE guy/video did a better job with his experiment, explanation, and summary numbers. A government lab probably isn't the best place to evaluate ASS.

(Repeating: SAE did not conduct the tests, it was the National Transportation Research Center/Oak Ridge National Laboratory.)

 

[Ratbert]

I think the EE guy/video did a better job with his experiment, explanation, and summary numbers. A lab probably isn't the best place to evaluate ASS.

(Repeating: SAE did not conduct the tests, it was the National Transportation Research Center.)

Note that the tests he's taking about were done over 2,300 miles. That should mitigate your previous concerns about ASS not lasting 100 miles.

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