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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

#201

Post by anthony_d »

david-given wrote: post #145
anthony_d wrote: post #72

Earlier quoted context omitted.

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…

(You need to specify whether you're US or UK. Different gallon sizes! It makes US MPG ratings seem significantly worse than UK ones.)

Yeah, I always forget about that. I'm in the US so I'm allowed to forget about the rest of the world, right?

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

#202

Post by lgieron »

[deleted] wrote: post #34
mpweiher wrote: post #22

Earlier quoted context omitted.

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]

Audi Q5 weights 1850 kg according to wikipedia (https://en.wikipedia.org/wiki/Audi_Q5), although this obviously depends on the engine. 2470 kg looks more like maximum allowed weight of car + passengers + cargo.

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

#203

Post by anthony_d »

switch007 wrote: post #135
anthony_d wrote: post #72

Earlier quoted context omitted.

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

I don't think they're especially good or bad, my point was just that they are almost exactly what Audi claimed.

After the VW news I'm rather happy I went with petrol. Actually I never gave diesel a thought because Audi doesn't sell A3 or A4 diesels in the US (at least dealers don't have them and the website doesn't show them).

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

#204

Post by mikeash »

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.

Tesla's range numbers for the Model S assume about 300Wh/mile average consumption. My average consumption so far over not quite 8,000 miles is 315Wh/mile.

It's hard to cheat in an electric car. Few people care about efficiency directly, but most electric car drivers care deeply about range, and range is just battery capacity multiplied by efficiency. If Tesla were cheating so they could lie about efficiency, Tesla owners would notice pretty much right away that they're not achieving the range they should.

The only practical way for Tesla to cheat would be to ship a larger battery than they say they do, and then fudge the numbers from there. Given the current cost of batteries, this would be an incredibly expensive cheat, and it would be tough to hide from the tinkerers who tear down battery packs to see how they're built.

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

#205

Post by mikeash »

yoz-y wrote: post #200
Bud wrote: post #82

Earlier quoted context omitted.

You "expect"? Could you perhaps cite any data, any at all? It's not like we don't have a LOT of Tesla owners out there who are obsessively testing this, every day. Do you think they're just all part of the conspiracy?

It is kind of weird that this is surfacing just now. There are magnitudes more VW owners than Tesla. Why have not the consumer studies revealed this a long time ago?

You have to put in a fair amount of effort to monitor the fuel efficiency of a gas (or diesel) car. It's not hard, but you have to keep manual records and do some math.

If an electric car is much less efficient than claimed, you'll notice as soon as you try to drive to the limit of your car's range, because it won't get there.

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

#206

Post by mikeash »

rebootthesystem wrote: post #98

It's called "real world driving". Look, this is no different from Tesla claiming a 280 miles range that nobody can achieve. Not saying it is right. What I am saying is: We need better tests.

It's not actually very hard to achieve rated range in a Tesla. You might need to refrain from flooring it at every opportunity and you might want to cut down from going 10MPH over the speed limit, but it's not a challenge.

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

#207

Post by kbenson »

mattlutze wrote: post #58
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...

The source of the data is actually www.spritmonitor.de, which is a self-reporting mileage tracking site (like www.fuelly.com). With ~501k vehicles tracked and 8.885B kilometers tracked, the site represents ~17k kilometers per car of user-reported mileage information. Is this the best, or a reliable source, of information to start the reckoning/witch hunt to come? I'm not sure.

Whether it's the most reliable or not, to me the indicated graph at least shows something massively different going on with some GM cars. Every other manufacturer ranges from achieving ~20% to 80% of their claimed fuel emissions improvements from 2008 to 2014, and then there's GM, all by itself with negative 40%.

That is, for GM cars alone, people are reporting not just a lack of increased fuel economy, but that it's gotten significantly worse. Whether it is accurate or not, it indicates something very wrong, either in the testing or in those cars, and that deserves some serious attention IMO.

Edit: s/fuel economy/fuel emissions/ Graph says economy, subtitle say emissions, text says emissions.

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

#209

Post by marze »

eveningcoffee wrote: post #168
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...

If you read carefully then the report actually does not provide any data about fuel economy. While they speak about fuel consumption and even speculate with numbers, this is not backed up by the data. Report contains only data about CO2 emissions.

Uh, it is the same. Fixed amount of carbon in a gallon of fuel, all will be emitted.

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

#210

Post by aianus »

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...

> Modern cars do better in rolling hills than on perfectly flat land, since they can cut fuel entirely on the downhill

This is physically impossible. Even if the car was perfectly efficient at overcoming the force of gravity on the uphill portions (which it is not), you cannot do better than flat terrain (unless by hilly you mean 'net downhill').

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