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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

#131

Post by debacle »

Someone1234 wrote: post #91
crazypyro wrote: post #39

Earlier quoted context omitted.

"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.

Does it matter however when it is systematic? This is going to sound backwards, but consider this: People buy cars based in part on MpG, however MpG is within itself an abstract thing (i.e. you don't actually get X miles per gallon, never did, never will too many other factors to include). So if everyone removes 4% from an abstract number, the entire market has shifted down, but the relative difference between two mo…

It definitely does in 2015 when you are comparing against cars that don't have an MPG.

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

#132

Post by brandon272 »

bonzini wrote: post #118
vkjv wrote: post #86

Earlier quoted context omitted.

I thought the same. In my anecdotal experience, drivers tend to get much lower than the manufacturer mileage because they optimize for things other than fuel economy (e.g., speed). My dad taught me lots of tips on conserving fuel and thankfully I've exceeded the sticker numbers on every car I've owned.

No matter how careful I am, it's hard for me to get lower than 130% of the fuel consumption reported by the manufacturer. Perhaps I can do 120% of the reported consumption at 90 km/h, but I can hardly get lower than 140% on the highway (130 km/h) and in city traffic.

I'm the same way. Even when I drive as conservatively as is safely possible I still can't get it lower than ~120%.

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

#133

Post by debacle »

joosters wrote: post #124

One problem with the report is that real-world driving styles might be linked to the type of car. So, small cars might perhaps be more likely used for short commutes, whereas larger cars could tend to have longer motorway journeys. One driving style is likely to be closer to the standard tests than the other. So, even if one car seems to perform worse, it could just be because of the average driving of that car.

That's a problem with a test, not a problem with the report.

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

#134

Post by jsprogrammer »

petercooper wrote: post #123

I never pay attention to fuel consumption figures as they have never represented reality in my case. My current Mercedes has an official rating of 40mpg, but I never get that out of it unless I literally sit at 55mph on a flat motorway and never change speed (impossible in the UK). Some journeys I go as low as 19mpg when it's driven as it's meant to be. All the Vauxhalls I had before were the same.

As it's meant to be? How is that? 40 to 19 is a huge gap.

Do you engage the throttle and brakes more than necessary?

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

#135

Post by switch007 »

anthony_d wrote: post #72
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've got an 2016 Audi A4. Audi claims 22mpg city, 32mpg highway and 26mpg combined. What I see is 24mpg city, 31mpg highway and 26mpg combined; I don't drive especially slow either. FWIW, I factory ordered a manual transmission so that may make a difference. I'm skeptical of cars that claim crazy high MPG ratings and performance cars claiming good MPG numbers, but for a standard car I do expect the numbers to be achi…

Those numbers (37.2 miles per imperial gallon) are in the 3.0 TDI territory for Audi in the British(/EU?) market. Many would be disappointed with 37.2 highway for any 2.0 diesel engine: look at the 'Real MPG Avg' column at http://www.honestjohn.co.uk/realmpg/audi/a4-b8-2008

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

#136

Post by ams6110 »

pjc50 wrote: post #69
cLeEOGPw wrote: post #65

Earlier quoted context omitted.

> except electric Why? You have just been shown corporate cheat on tests. Why you would ever assume this has something to do with fuel type? I expect Tesla cheat as much as MB or BMW in their "range" test. And if you believe otherwise you are just someone who doesn't learn from his experience.

Tesla have, on a couple of occasions, experienced the opposite: a journalist does a range test and falsifies the result downwards by unrealistic driving conditions. On one occasion they used the car's telemetry to disprove the review. Top Gear got complaints for doing the same thing to (I think) a Leaf.

Top Gear did it with a Tesla Roadster.

But really, Tesla develop cars with high performance characteristics, and then people complain about "unrealistic driving conditions" when people drive them as they are designed?

Tesla could easily program the cars to accelerate moderately and with maximum energy efficiency, but they would't be able to command $80,000 price tags if they did that.

People who spend Tesla, Mercedes, or BMW money on a car, by and large, don't give a shit about economy.

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

#137

Post by _ambigu0us_ »

simias wrote: post #73
tonylemesmer wrote: post #33

Earlier quoted context omitted.

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

If you make the pedal more sensitive (increase the resulting travel per pedal press) you'll make it harder to apply a precise amount of braking power which doesn't sound like a nice feature. I suppose you could have a more clever system that would move the brake faster until it touches the disc and then behave normally but I suppose that for such a critical system constructors and regulators are very conservative. Th…

> If you make the pedal more sensitive (increase the resulting travel per pedal press) you'll make it harder to apply a precise amount of braking power which doesn't sound like a nice feature.

If you've tried hopping in a car from the past few years after driving a much older car you (and you passengers) will have probably noticed this! It's very common in modern cars to have much shorter brake pedal travel, so what would bring you to a gentle stop in an older car will be somewhat more abrupt in a modern car.

This is achieved by having a shorter travel pedal, which is then heavily assisted by the brake servos so it is not horribly heavy to apply. This is nominally for safety's sake, as it reduces the time between seeing a obstacle and the brakes being fully applied. And since all recent cars have anti-lock braking and stability systems it doesn't matter so much if the driver can't control the braking pressure quite as precisely.

> I suppose you could have a more clever system that would move the brake faster until it touches the disc and then behave normally but I suppose that for such a critical system constructors and regulators are very conservative.

Exactly, as I mentioned to the other commenter, it's preferable to have a simple, non powered mechanical system in place to stop the car in the event of bad things happening. Adding extra bits to this system, with the vast R+D cost involved, for marginal increases in fuel economy would be hard to justify for most car manufacturers (especially since the fuel economy saving would benefit the users pockets, not theirs).

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

#139

Post by ksk »

001sky wrote: post #68
rtpg wrote: post #54

Earlier quoted context omitted.

Well sorry for being a fool then. It's impossible to investigate everything about every part of our lives, and personally I feel a bit cheated by these revelations. I think most people are aware there could be cheating, but not on the scale being claimed. I don't think it's unreasonable to have placed a bit of trust in the number.

that's no excuse, its basically ignorance. not personal critique, but still lots of people follow blindly things they don't understand.

That's like saying someone threw a rock at you and because you didn't look around before it hit you, its your fault. The cheating is the problem, not the fact that people are ignorant about it.

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

#140

Post by michaelt »

cLeEOGPw wrote: post #65
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.

> except electric Why? You have just been shown corporate cheat on tests. Why you would ever assume this has something to do with fuel type? I expect Tesla cheat as much as MB or BMW in their "range" test. And if you believe otherwise you are just someone who doesn't learn from his experience.

  I expect Tesla cheat as much as MB or 
  BMW in their "range" test.
Many lithium-ion batteries lose capacity with more charge cycles - 20% after 500 charge-discharge cycles would be typical [1] although there are longer-life batteries - so manufacturers who value their reputations design in enough overhead that the battery will still have enough capacity after a few years / when the product reaches the end of its design life.

Personally I'd expect a tesla that had just rolled off the production line to exceed the specified range easily.

[1] http://industrial.panasonic.com/lecs/www-data/pdf2/ACA4000/A...

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