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

#151

Post by gambiting » Wed, Sep 30, 2015, 3:47 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 2013 Qashqai 1.6dCi 4x4 weighs exactly 1630kg and uses between 5-6 litres of diesel for every 100km traveled, depending how aggressively I drive it. And no, that's not the value from the car's computer, that's an actual usage.

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

#152

Post by tremon » Wed, Sep 30, 2015, 3:47 PM UTC

Zelphyr wrote: post #102

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.

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 traffic light more time to turn green. You spend less fuel trying to reach the stop line, and spend less fuel accelerating again. Bonus points for shifting down while decelerating.

- Keep tires well-inflated and oil levels up. Less friction means less wasted energy on both.

- Choose the highest gear when cruising. Most cars since 1990 can do 50kmh (30mph) even in fifth gear, as long as you don't need to accelerate.

- Drive slower. Most car engines are most efficient around 3500 rpm, which maps to somewhere between 90-110 kmh (60-70mph). Most highways allow for a higher speed. Diesel engines have their optimum at 2000 rpm, or so I've been told.

Of course most of this works best with a stick shift. I've never driven an automatic.

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

#153

Post by gamblor956 » Wed, Sep 30, 2015, 3:49 PM UTC

MrRadar wrote: post #35

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...

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.

A larger part of fuel consumption is driving behavior. My Ford Fusion (non-hybrid) only gets about 15 mpg in city/rush-hour driving because I drive very aggressively...but nearly 40 mpg on the freeway using cruise control (set to 75-80mph).

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

#154

Post by joosters » Wed, Sep 30, 2015, 3:50 PM UTC

debacle wrote: post #133

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.

No. The emissions test has to pick a certain kind of driving style. It can't emulate them all.

The report, on the other hand, could try to compare like-for-like. For example, they could give separate results for high-mileage drivers and low-mileage drivers. Or split the results by average speed, to try and isolate long-distance motorway drivers from short commutes.

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

#155

Post by dmoo » Wed, Sep 30, 2015, 3:51 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...

Just one bit of evidence to the contrary. I have filled the 70 litre tank in a 1.6tdi VW Passat and driven 1400 km with 5 occupants and luggage. This was mainly European motorway driving.

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

#156

Post by slasaus » Wed, Sep 30, 2015, 3:52 PM UTC

slasaus wrote: post #44

Zigurd wrote: post #25

Earlier quoted context omitted.

This is a very good bet. The "defeat device" turns out to be using a feature of the ECU platform provided by the ECU supplier. It would be surprising to find that VW was the only maker to cheat, when the cheating mechanism was available to everyone. There are some markets, like voting machines, where requiring open, buildable, verifiable code is good practice. Cars might be another.

I was thinking of voting machines as well and think publicly verifiable code and hardware would be a good thing for cars (I don't think it's good enough for large scale elections, but that's another topic). See this story about the need for open source for large publicly used systems: http://www.nytimes.com/2015/09/23/nyregion/volkswagens-diese...

ps. just reading this in a post from Bruce Schneier[1] that is currently on the frontpage as well[2] which is about cheating software as used by car manufacturers and the IoT that is coming up:

    Voting machines could appear to work perfectly -- 
    except during the first Tuesday of November, when it 
    undetectably switches a few percent of votes from one 
    party's candidates to another's.

[1] https://www.schneier.com/blog/archives/2015/09/volkswagen_an...

[2] https://news.ycombinator.com/item?id=10304428

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

#157

Post by mfringel » Wed, Sep 30, 2015, 3:52 PM UTC

001sky wrote: post #141

dtparr wrote: post #111

Earlier quoted context omitted.

Of course they do. People have limited time and energy and can't possibly be expected to have a good enough understanding of everything they touch in their daily lives to be able to "understand" them well enough to have sufficiently calibrated bullshit detectors for them all. Maybe you're an expert in ICEs and this was obvious to you. Would you notice if your cell phone charger was actually pulling 10 amps out of the…

They didn't call those bands "rage against the machine" and "public enemy" for nuthin now did they? I mean, in all seriousness, why be so serious? Simple points need to be understood, not simply dismissed out of hand. In theory everything the government or your employer tells you is true. In reality, they have alot to gain from asymetric information distribution, both in terms of negotiating financial outcomes but al…

Have you checked your keyboard's electrical path for surveillance equipment this morning?

Did you test your water for drugs this morning?

Did you check them yesterday?

We all live at certain layers of abstraction.

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

#158

Post by vonmoltke » Wed, Sep 30, 2015, 3:55 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...

> You cant have a 1,5t of a car and expect it to use only 5l/100km

So you are telling me that my actual, measured fuel consumption numbers of 4.25l/100km on flat highways in the US South are impossible? I have a diesel Passat (yes, one of the NOx Boxes :P) and can get from Dallas, TX to Pensacola, FL (650 mi) without refueling and with a decent reserve (~2 gallons) still in the tank.

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

#159

Post by userbinator » Wed, Sep 30, 2015, 3:56 PM UTC

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…

Choose the highest gear when cruising

You can do this for automatics too - you just have to learn where the shift points are and drive at the right speed. Lift up on the accelerator quickly to upshift, press it down quickly to downshift. One thing that I notice easily when riding is when the driver is constantly staying at only a few km/h slower than the shift point, causing the engine to spin faster and consume more fuel than necessary. It often means the car is louder and vibrates more too, so not a good thing overall.

This is harder to do for newer models with quieter engines and smoother shifts but older automatics have very noticeable shifts and engine noise to judge whether you're near the bottom or top of each gear. It's very noticeable in larger trucks and buses.

Edit: another point I'll add to the list is traffic light phasing - look far ahead and observe the timing of the lights, and adjust your speed so that you're not going too fast (you'll arrive at a light before it turns green) or too slow (it'll turn red very shortly before you arrive). Obviously, you should do this only if traffic permits, but it's a great "trick" (not so much a weird one) when you can get from your origin to your destination at a constant speed with nearly no stops.

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

#160

Post by PythonicAlpha » Wed, Sep 30, 2015, 3:57 PM UTC

The problem with the environmental problems (currently with VW) and the fuel consumption is, that particularly in the EU, the governments for years (if not decades) turned a totally blind eye on the car manufacturers.

The problems with the emission measuring and also fuel measuring was known for long now and in the EU, many wanted to change the measuring methods -- but for example the German government did always block such advances.

In my opinion, not only the car manufactures are guilty, but even more the politicians that made it very easy for them to cheat on us all. The additional expenses (at the gas station and with the bad air) carry the consumers.

VW is only the tip of the iceberg.