Study: Some car models consuming around 50% more fuel than official results • Hacker News Board

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

#31

Post by mpweiher » Wed, Sep 30, 2015, 1:33 PM UTC

emp_zealoth wrote: post #16

larrydag wrote: post #10

Earlier quoted context omitted.

I'm guessing its across the industry. I'm wondering if this is the tip of the iceberg.

Im pretty sure its just a case of completely out of control rules - they became impossible to follow, so everyone just decided to "play along"

Also rules that are in conflict. To get good mileage and corresponding low CO2 emissions, you need ultra lean mixtures. Alas, ultra lean mixtures produce more NOx.

You want low NOx emissions, you need richer mixtures, and thus higher fuel consumption and higher CO2 emissions.

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

#32

Post by padelt » Wed, Sep 30, 2015, 1:35 PM UTC

happyscrappy wrote: post #19

padelt wrote: post #11

Earlier quoted context omitted.

> Europe was really led astray when they were told that diesels were better for the environment Were we led astray? Or are we discussing the last few percentages beyond an actual advantage over gasoline engines?

The reason air pollution is so much worse in European cities than American ones is largely due to diesel passenger vehicles.

That both suprises me, do you have any sources? Honest question, both seem counterintuitive. Maybe I am actually fed enough "feelgood" information in the past.

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

#33

Post by tonylemesmer » Wed, Sep 30, 2015, 1:35 PM UTC

_ambigu0us_ wrote: post #24

etimberg wrote: post #5

I went through to the actual report ( http://www.transportenvironment.org/sites/te/files/publicati... ) and found an infographic (figure 8) that shows some of the methods manufacturers can use to defeat tests. "Pushing the brake pads fully into the callipers reduces rolling resistance" is apparently one way. That makes me ask the question, why don't we do this already? If it reduces rolling resistance it probably als…

In car braking systems the pedal movement from depressed to pressed corresponds to a very small ( With the brake cylinder fully compressed (as they did for the test), it requires several full pumps of the pedal to bring the pad into contact with the disk. This increases braking distance, which is generally considered a bad thing.

The travel from a single pedal press is small, but its probably a solvable problem. It just needs a different design.

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

#34

Post by [deleted] » Wed, Sep 30, 2015, 1:35 PM UTC

mpweiher wrote: post #22

emp_zealoth wrote: post #8

Earlier quoted context omitted.

Or maybe we abolish nonsensical, contrary requirements? Whoever actaully believed the fuel consumption figures is a fool. You cant have a 1,5t of a car and expect it to use only 5l/100km. That's a good rate for a goddamn motorbike (450ccm,one piston, dont exceed 90 km/h and you might reach 4,5l/100km) Its one fifth of the mass...

I actually drove my Golf TDI at around the level of 5l/100km in Berlin for many years. Carefully. My girlfriend's Polo is significantly below that. Of course, these cars aren't ton and a half, but more around a ton.

[deleted]

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

#35

Post by MrRadar » Wed, Sep 30, 2015, 1:36 PM UTC

emp_zealoth wrote: post #8

yc1010 wrote: post #2

"On average, two-thirds of the claimed gains in CO2 emissions and fuel consumption since 2008 have been delivered through manipulating tests" How deep does this rabbit hole go :( Here in Ireland the motortax for cars newer than 2008 is based on CO2 emissions, if motorists find their tax rising due to cheating by car manufacturers thats an unexpected and direct cost to their wallets.

Or maybe we abolish nonsensical, contrary requirements? Whoever actaully believed the fuel consumption figures is a fool. You cant have a 1,5t of a car and expect it to use only 5l/100km. That's a good rate for a goddamn motorbike (450ccm,one piston, dont exceed 90 km/h and you might reach 4,5l/100km) Its one fifth of the mass...

My Chevrolet Sonic (with a 1.4L turbocharged gasoline engine and a curb weight of around 1.4 US tons or 1.5 metric tons) gets 42-ish MPG (5.6 L/100 km) during the summer and my driving conditions aren't even ideal (half my commute is highway speeds with stoplights). A Toyota Prius (Auris) could probably get more than 50 MPG (less than 4.7 L/100 km) on the same route.

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

#36

Post by pbhjpbhj » Wed, Sep 30, 2015, 1:37 PM UTC

emp_zealoth wrote: post #15

etimberg wrote: post #5

I went through to the actual report ( http://www.transportenvironment.org/sites/te/files/publicati... ) and found an infographic (figure 8) that shows some of the methods manufacturers can use to defeat tests. "Pushing the brake pads fully into the callipers reduces rolling resistance" is apparently one way. That makes me ask the question, why don't we do this already? If it reduces rolling resistance it probably als…

The brake pads and jaws get contaminated with dust and the like,making them stick a little. My guess is they get disassembled before test and cleaned perfectly.

How much benefit is it, wonder if having a small compressed air squirter - like a headlight washer - would pay off (in terms of fuel savings) or not.

Would be interesting to know what designs of pads/jaws dissipate the contaminants better?

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

#37

Post by [deleted] » Wed, Sep 30, 2015, 1:38 PM UTC

Bud wrote: post #29

If you read the full report, the automaker with by far the largest gap between its claimed improvements in fuel economy and its actual on-the-road performance is General Motors. Much worse than VW and Mercedes (who also did very poorly), by this measure. A reckoning is coming. source: see page 13, here http://www.transportenvironment.org/sites/te/files/publicati...

[deleted]

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

#38

Post by scrumper » Wed, Sep 30, 2015, 1:40 PM UTC

happyscrappy wrote: post #19

padelt wrote: post #11

Earlier quoted context omitted.

> Europe was really led astray when they were told that diesels were better for the environment Were we led astray? Or are we discussing the last few percentages beyond an actual advantage over gasoline engines?

The reason air pollution is so much worse in European cities than American ones is largely due to diesel passenger vehicles.

See for example Paris's recent (yesterday?) "no car day" in the center. The city's usual blanket of smog is gone. France of course having the highest %age of diesel cars in its passenger fleet of any country.

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

#39

Post by crazypyro » Wed, Sep 30, 2015, 1:40 PM UTC

Bud wrote: post #29

If you read the full report, the automaker with by far the largest gap between its claimed improvements in fuel economy and its actual on-the-road performance is General Motors. Much worse than VW and Mercedes (who also did very poorly), by this measure. A reckoning is coming. source: see page 13, here http://www.transportenvironment.org/sites/te/files/publicati...

"3. Deducting 4% from measured results

Bizarrely the NEDC procedure allows carmakers to actually declare (use) a value 4% lower than the one measured. The provision is designed to minimize the testing burden but is being abused by carmakers to declare lower test results systematically."

I wonder if there is a person that didn't expect this to happen.

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

#40

Post by knowaveragejoe » Wed, Sep 30, 2015, 1:41 PM UTC

eterm wrote: post #20

axx wrote: post #14

I think we all should agree that this is the same for every car manufacturer (except electric). Sure, european manufacturers are the target now, but i expect same results from all other manufacturers (including asian and american). Lab results never represent real street results. How could they? People drive differently and the outcome is based on many aspects that you can't reproduce in lab conditions.

You are obfuscating the issue here. The issue isn't that we can't "represent real street results", the issue is that manufacturers took deliberate steps to alter car behaviour with the intention of obtaining better test results than would be present outside the tests.

But the results they're aiming for are ostensibly based on some measure that represents "real street" results. Otherwise, why the hell do we have these measures in the first place?