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Fuel Efficiency Numbers Overstate MPG More For Cars With Small Engines
whoever57 writes: All official numbers for fuel economy in the EU typically overstate the miles-per-gallon figure that drivers can expect to achieve in typical driving. A recent study confirmed this once again. However, what the study also found was that MPG figures are more unrealistic for cars with smaller engines than for cars with larger engines. Actual MPG figures achieved based on typical drives for cars with small engines could be as much as 36% under the official number, while those cars with 3-liter engines would typically achieve 15% less than the official figure.
These discrepancies need to be accounted for if we're going to be serious about regulating fuel efficiency. But then, we should be using gallons-per-mile instead of miles-per-gallon, too.
"But then, we should be using gallons-per-mile instead of miles-per-gallon, too".
No. You should be using litres per kilometer. Especially so when talking about the EU.
The numbers are not overstated based on the test criteria. It is the test criteria that does not cover the real world operating conditions. Change the test requirements, and you'll change the results and therefore the rating.
If you try to push a small engine to drive like a larger one, you'll be accelerating harder, therefore using more fuel than under normal acceleration.
In similar manner, some years ago, I had a Grand Cherokee that my wife couldn't get more than 11mpg out of, while I could do 17mpg.
We have different driving styles. She is a leadfoot, while I drive like I have an uncooked egg between my foot and the gas pedal.
Perhaps this article might better be titled "Want better gas mileage? Don't drive like a gashole."
The shepherds did so well protecting the flock that the sheep no longer believed that wolves existed.
Yes, because there is no reason to ever have a stop sign, it's purely to annoy skilful drivers like you.
To have a right to do a thing is not at all the same as to be right in doing it
Probably most of it comes down to driving style. People who are used to older cars with bigger engines will probably think a new model with a small engine is gutless and will floor the accelerator to make it go faster. Anecdotally, I drive a 2005 Civic Hybrid, which was originally rated for ~46 MPG with the "less realistic" measure EPA used back then. I've driven it 170k miles now and that is in fact its lifetime average - it has two trip odometers and I never reset one of them. However back when these were still pretty new I read reports of people who complained about getting only ~33 MPG out of an identical car. The only reasonable explanation is that they were flooring it between stoplights and generally ignoring the instantaneous and cumulative MPG display the car gives you.
Basically people are impatient and don't know how to drive efficiently. It took me a few months to really get into the groove with mine and I still have to make sure I've got plenty of room to pass on the highway, but it's certainly doable.
Hail Eris, full of mischief...
E pluribus sanguinem
It's true, though. For most cars, fuel economy declines as speeds climb past 55-60mph (wind resistance being non-linear). You're trading off fuel for time - get there faster, but use more fuel. We should let people make that tradeoff for themselves, however. Just price fuel appropriately (including the externalities of climate, military expenditures, etc.), and let drivers decide.
would it not be better to simplify a volume divided by a length to an area. Gallons/mile is best represented in represented in hectates or furlongs^2.
Some drink at the fountain of knowledge. Others just gargle.
1 US gallon / mile = 0.00364583333 sq inches
Some drink at the fountain of knowledge. Others just gargle.
The study is by Emission Analytics, and here is the original link (as opposed to TFA from The Telegraph).
Note some misleading elements from TFA: they show only the three smaller classes for UK cars, seemingly indicating that small cars are the worst gas guzzlers, whereas cars with higher engine sizes are actually much worse according to the original study (see the graph). So the lesson is: still buy a small car, just not a very small one for best fuel efficiency.
Another interesting bit that is not in TFA is that the data for US cars is different: there, cars between 1 and 3 liters in volume (I assume this is the large majority of the car pool) have less than half the mileage. Also, the smallest US cars are actually the most efficient of any class, even though their efficiency is below UK average.
Victims of 9/11: <3000. Traffic in the US: >30,000/y
What possible benefit is there to taxing fuel, other than to hand more money to the government to waste?
Oh, yeah, I forgot, it lets you force people into small cars they don't want, or force poor people onto buses.
Why do you hate the poor? What did they ever do to you?
(that being the USofA) is to worry about how far we can go on a tank of fuel. This is a throwback to the days when trips of any significant distance could easily leave you stranded between fueling stations (which used to be as much as hundreds of miles apart)
In that case, knowing distance per unit of fuel is more important than fuel per unit of distance.
In Europe, where distances are SIGNIFCANTLY shorter it is much more interesting to worry about the cost of the trip, especially when public transport options are close competitors in price. In this case the unit of fuel per unit of distance makes a much easier comparison.
This is what happens when uneducated, uninformed Peter-Principle bureaucrats dictate fuel efficiency standards without checking with real engineers to find out if it's even possible.
For many of us in the USA, you're assumption about what we care about is bullshit wrong.
I live in Portland, Oregon. If I'm going north or south, I'm sometimes interested in mpg, but it isn't a big thing. Never very far from an Interstate highway in those directions.
But if I'm going northeast or southwest, mpg is critical, because there are too many back roads in the Washington and Oregon outback where running out of gas would put one in serious danger, and not be just a bit of an inconvenience. Having to hike 50 miles to the nearest gas station in the summer heat with no water or shade to be found is something to avoid.
This is not unique to Oregon. There are a lot of places throughout the USA where people often drive into what passes these days for wilderness, where if you don't estimate how many miles you've got left in the tank, you could end up in an unhealthy or even deadly experience.
MPG is the sensible measure to use in North America. Perhaps someday that will become kpl, but it will never make sense to use gallons per mile or kilometers per liter.
Now fuel for construction equipment that might travel all of 10 miles in an 8 hour shift needs to be measured in gallons per hour, but that's an entirely different thing.
Will
Now lets try the same using the metric system:
1 litre / kilometre = 1 sq millimetre
That is another win for the metric system in my book.
What possible benefit is there to taxing fuel, other than to hand more money to the government to waste?
Oh, yeah, I forgot, it lets you force people into small cars they don't want, or force poor people onto buses.
Why do you hate the poor? What did they ever do to you?
The rationale for taxing fuel is to capture the externalities (pollution, climate, military costs) of using that fuel. The point about the regressiveness of the gas tax is valid, so we should raise the gas tax, but add a refundable credit to income taxes for it, to remove the regressiveness.
My personal favorite is how Americans measure pressure (such as in tires): pounds per square inch. It is so bizarre, it is beautiful...
The "pounds" are pounds of force (lbf), of course, but I doubt, an average person (be he American or European) can articulate the difference between mass and weight...
In Soviet Washington the swamp drains you.
The places I want to go are NEVER on the direct route between A and B. Oregon sunstones are more than 70 miles from the nearest gas station, and the last 30 miles are gravel. That's 140 miles of poor gas milage with no chance for a fill up.
Back roads to trail heads at Paulina Lake, into the Strawberry Mountains, or the fossil beds are even worse.
Once you get out of Mama's basement, there is a wonderful world out there to explore. Using MPG rather than some other fuel consumption measure makes those explorations just a little bit easier.
Quite apart from the random ad hominem, saying that we should use MPG because it's marginally more useful for a tiny share of total trips taken in the US, and only in those cases for the small portion of cars that don't have distance to empty available, and for the drivers of those cars who can't be bothered to fill up at a gas station before venturing out on a 150 mile round trip, just doesn't make sense. Somewhere, there might be someone who has once made a trip in a car where the odometer had been customized to read in rods, and the only local gas station had a software problem with the pumps, so they read in hogsheads for a day. That doesn't mean Grandpa Simpson was right.
Finally, using MPG doesn't really tell you anything for the purpose you're talking about. You care about RANGE, not fuel economy. If you're starting off on that 140 mile round trip without gas stations, and your gas gauge reads half full, and your car gets 25MPG, you could be in great shape (if you have a 20 gallon tank) or screwed (if you have a 12 gallon tank).