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Study: Some car models consuming around 50% more fuel than official results

transportenvironment.org

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Re: Study: Some car models consuming around 50% more fuel than official results

#231

Post by zardo »

awjr wrote: post #107

Ok let's be real here, if we put the "pollution" taxes onto fuel and not on the design of the car, this problem, in effect, goes away. There is still the issue that high efficiency, usually means running the engine at high temperatures which generates far more NOx gases. We should be taxing the amount of fuel used.

That works for CO2, because there is no technology to mitigate CO2 release from combustion. But that isn't the case for particulate matter, carbon monoxide, or nitrogen oxides. You can't put a NOx tax on diesel because the amount of NOx you produce from burning a given quantity of diesel will vary by two orders of magnitude depending on the pollution controls.

Re: Study: Some car models consuming around 50% more fuel than official results

#232

Post by Theodores »

TylerE wrote: post #191
userbinator wrote: post #166

Earlier quoted context omitted.

Are you in an area with much hilly terrain? That'll definitely increase fuel consumption significantly.

Actually, it depends. Modern cars do better in rolling hills than on perfectly flat land, since they can cut fuel entirely on the downhill, and the climbs don't require that much extra fuel over just maintaining speed. Now, mountains are another story, of course. Some good stuff in this SE question: http://physics.stackexchange.com/questions/6220/can-a-car-ge...

I cannot imagine a cyclist imagining this to be true!

Obviously aerodynamics play a part, however the cyclist's 'engine is cut' on the downhill and on big cross country roads no brakes need be used on the descents. When the 'engine' is on it goes at a certain not-quite-racing amount whether up hill or on the flat. But place a hill in the way of A to B and vastly more 'fuel' is used than A to B 'going the flat way'.

Re: Study: Some car models consuming around 50% more fuel than official results

#233

Post by TheCoelacanth »

JonFish85 wrote: post #177
fithisux wrote: post #17

Earlier quoted context omitted.

Not their wallets. why should they pay for the fraud of corporates? Let the corporates replace cars .

One way or another, regular folks will pay for it. If it's directly by paying this tax, that's straight forward. Otherwise, the company will take the hit, and the cost will flow towards stock-holders, which in general tend to be unions, 401k plans and such. How much of your 401k are you willing to lose due to that cost? How much of your parents' 401k/union pensions is OK to forfeit?

That sounds like an argument for never punishing corporations for anything, which is clearly unworkable.

Pension and 401k plans are typically diversified across a broad range of stocks, so they won't be heavily impacted by a single company's stock price dropping. On the other hand, executives and board members, who are actually responsible for the company's actions, will typically have a large amount of that company's stock so they will be much more heavily impacted by the stock price dropping.

Re: Study: Some car models consuming around 50% more fuel than official results

#234

Post by kuschku »

pjc50 wrote: post #125
_pmf_ wrote: post #116

Earlier quoted context omitted.

All European manufacturers except Renault and BMW are hellbent on not offering attractive E mobility solutions, despite really expensive and extensive internal research programs. We in Germany have a large numbers of Smart cars in car sharing companies that are sponsored by Daimler, but it's not yet economically viable to actually buy an E-Smart (if you've driven one, it's not bad at all).

It's strange. Europe should be a better market for electric and hybrid cars, given the higher petrol costs, but I guess the high purchase costs are putting people off. I'd buy one if I did enough miles. It's not worth it for a few thousand a year. Even having a petrol car sitting on my drive is an expense of marginal justifiability.

The other issue is that in europe the group of people who are most likely to buy an electric car usually just bike or use public transit instead.

Re: Study: Some car models consuming around 50% more fuel than official results

#235

Post by kbenson »

rnovak wrote: post #229
kbenson wrote: post #212

Earlier quoted context omitted.

But that's actually irrelevant for the cited report. What the referenced graph says is that from 2008 to 2014, auto manufacturers declared a certain increase in emissions/economy, real world people reported a different amount, and those amounted to, unique to GM in this report, a negative percentage in how well they achieved their claims. That is, on average, GM car fuel economy got worse over this period, or people'…

It's not irrelevant at all. Manufacturers report fuel consumption during a controlled environment, with specific driving habits, etc. Real world people drive insane (at least in the US), and most wouldn't even re-pass their drivers-license test, so most assuredly do not have the best driving habits. So drawing the conclusion that manufacturers are "lying" from the discrepancies between those two data sets is ridiculo…

It's irrelevant because unless both a) people changed their driving habits on average over that time frame to cause more emissions and b) that change was primarily limited to drivers of GM vehicles, then driver habits do nothing to explain the data.

> So drawing the conclusion that manufacturers are "lying" from the discrepancies between those two data sets is ridiculous.

Perhaps you should pay attention to actually what I said, not what you think I said. I didn't say GM was lying, I implied their numbers deserve extra scrutiny.

Re: Study: Some car models consuming around 50% more fuel than official results

#237

Post by ucsdrake »

henningo wrote: post #221

I think it is a bit unfair to just blame the manufacturers. The legislation could likely be changed to make for a more robust test approach. After all, it is engineers we are talking about here, if they are given a task to optimize an engine's emissions and fuel consumption to a specific drive cycle they will do it. But then of course you have the ethical aspects which I won't go into. A computer science analogy to t…

"A computer science analogy to this would be if I gave you an uncompressed image and you had to develop a compression algorithm that made the image as small as possible, you could likely come up with a really good solution. But your algorithm most likely wouldn't do as well on any other image."

That analogy doesn't hold. It's more akin to developing two compression algorithms, one for the general case, and a specific algorithm which is used only when your image is detected for better than the general compression performance use case.

It is entirely fair to blame the manufacturers for this. Gaming emissions results required effort to accomplish, and is completely unethical from an engineering standpoint.

Re: Study: Some car models consuming around 50% more fuel than official results

#238

Post by mikeash »

arasmussen wrote: post #224
acomjean wrote: post #222

Wait a second.. When I bought my car (10 years ago) and read reviews, a lot of them say here's what the epa said you'd get for mileage, and heres what we actually got. There is always a difference (maybe 10%). But if it claims 30 mpg and you are getting 17 , I like to think more than few people might notice. Part of the reason VW was accused of cheating on emissions was it helped mileage. edit: as pointed out, its 50…

50% more fuel than official results would be like claims 30 mpg and actually getting 22.5 mpg.

Consuming 50% more fuel than 30MPG is 20MPG, not 22.5MPG: 30 miles divided by 1.5 gallons equals 20 miles/gallon.

Re: Study: Some car models consuming around 50% more fuel than official results

#239

Post by S_A_P »

tremon wrote: post #152
Zelphyr wrote: post #102

Earlier quoted context omitted.

Care to share some of those tips?

This is by no means an exhaustive list, nor an authoritative one. Would love to hear other's thoughts on these: - When accelerating, try not to over-extend the throttle. If the engine is at 2k rpm, you get just as much acceleration from 30% throttle as 100%, at half the fuel cost. - Release the throttle well before you reach a traffic light/stop sign. Deceleration by engine will cause a smoother stop and gives the tr…

ICE and Diesel engines are most efficient at full throttle. There have been some tests that show, in certain conditions, that using full throttle to get to speed and then maintaining speed is a more efficient way to drive than gradual acceleration.

Re: Study: Some car models consuming around 50% more fuel than official results

#240

Post by [deleted] »

ucsdrake wrote: post #237
henningo wrote: post #221

I think it is a bit unfair to just blame the manufacturers. The legislation could likely be changed to make for a more robust test approach. After all, it is engineers we are talking about here, if they are given a task to optimize an engine's emissions and fuel consumption to a specific drive cycle they will do it. But then of course you have the ethical aspects which I won't go into. A computer science analogy to t…

"A computer science analogy to this would be if I gave you an uncompressed image and you had to develop a compression algorithm that made the image as small as possible, you could likely come up with a really good solution. But your algorithm most likely wouldn't do as well on any other image." That analogy doesn't hold. It's more akin to developing two compression algorithms, one for the general case, and a specific…

[deleted]
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