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2 In 3 Misunderstand Gas Mileage; Here's Why
thecarchik sends in this piece, which was published last March but remains timely: "OK, so here's a little test: Which saves more gasoline, going from 10 to 20 mpg, or going from 33 to 50 mpg? If you're like most Americans, you picked the second one. But, in fact, that's exactly backwards. Over any given mileage, replacing a 10-mpg vehicle with one that gets 20 mpg saves five times the gasoline that replacing a 33-mpg vehicle with one that gets 50 does. Last summer, Duke University's Fuqua School of Business released a study that shows how much damage comes from using MPG instead of consumption to measure how green a car is. Management professors Richard Larick and Jack Soll's experiments proved that consumers thought fuel consumption was cut at an even rate as mileage increased."
I get that the 1st one is a 100% increase while the other is only 50% but you still get a better deal and less pollution by buying the 50 mpg car (if the price is the same).
So which saves more gasoline? the 2nd one ...
Breaking: In an astounding fit of partial international cooperation and scientific rationality, the US adopts a mostly metric measure of resource use: the milliliter per mile, or the mlpm
For example:
10MPG = 378 mlpm
20MPG = 189 mlpm
33MPG = 115 mlpm
50MPG = 76 mlpm
90MPG = 42 mlpm
The unit is linear, easy to understand, with numbers everyone can grasp (40-400 ish), and most important, it slowly creeps the US mind toward the metric system, one small step at a time! What a breakthrough! When the cars fly, we can try for using km, not miles.
Also, mlpm helps put the idea that gasoline is a great resource, to be used sparingly, by the milliliter, as opposed to "by the gallon" like 7eleven slurpies.
Sadly, in all seriousness, from TFA "Consumption instead of mileage? Nah. Dumb idea. Never work. [sigh]" Probably have to agree with this. Not because it's a dumb idea, but because Americans with the social and business systems in place have shown repeatedly that they will hold onto current ideas so strongly even in the face of overwhelming and obvious evidence showing them to be wrong. Only the real American idol will effect real change in the US system, the dollar.
I always thought that measuring it Euro-way - in, for example, gallons per 100 miles - would me more practical and clear.
Though it may not be obvious why to someone in a metropolitan area or Europe.
MPG is the more useful number when you need to figure out what the range of a vehicle is (and perhaps if you'll be able to reach the next station). In the western US it's not unheard of to find yourself 100 miles from any gas station.
"Prefiero morir de pie que vivir siempre arrodillado!"
Yes, changing the units will most definitely help. The units we should change to are the ones we already use here above the border: liters per 100 km. Going from 20 L/100k to 15 L/100k saves just as much as going from 10 L/100k to 5 L/100k. In most people's lives, the distance you need to travel is constant, not the amount of money you have to spend on fuel, so fuel per distance is much more logical anyway.
Which saves more gasoline, going from 10 to 20 mpg, or going from 33 to 50 mpg?
people answer incorrectly because the question is academic. what matters is that people know a higher MPG is better, which i think almost everyone does.
If you go from 10 to 20 mpg, youre still less than the 33 mpg lower limit in the second case, so the second option "saves more gas". If the question is "which is a bigger improvement in fuel economy", then the answer is the first one.
In fact, the two cases are not interchangeable. Suppose the problem is dressed up a little: you have two cars that you use on a regular basis (this is not negotiable), but only enough money to replace one of them. One car gets 33MPG, and the other gets 10MPG. If you replace the 33MPG car, you can get a 50MPG vehicle. If you replace the 10MPG, you can get a 20MPG vehicle. Which would save more gas, replacing the 33MPG car or the 10MPG car?
Palm trees and 8
My Accord gets about 10L/100km, or 0.01m^3/100000m or 1e-7 m^2. This is equivalent to one tenth of a square millimetre.
Which means a strip of gasoline down the centre of the lane, with a cross-sectional area of one tenth of a square millimetre, would be enough to power my car as it drives.
We're talking about North America, a typical vehicle gets 300 miles on a tank of gas. And 0 miles on a tank of diesel.
Don't get me wrong, if you're looking at replacing a perfectly good car with a new car, knowing how much better that car is is compare to your old car is a very useful thing.
That said, if you need a new car anyway, it really doesn't matter that the difference between a 10 mpg car and a 20 mpg car is higher than the difference between a 50 mpg car and a 33 mpg car. I 50 mpg car is still the best choice. No you probably shouldn't throw out your 6 month old 33 mpg car to get a 50 mpg car, and no you shouldn't say "I can't afford the 50 mpg car so I'm going to stick with the 10 even though I can afford the 20", but while mpg doesn't scale linearly, 50 is still better than 33.
Yes, of course. But how many 3 ton Suburbans do you see on the freeway during "rush" hour idling in stopped traffic with a single guy in it wearing a tie. He is not going to a construction job, hauling a load of bricks or a pallet of 50 25# sacks of tile grout, he is likely a financial analyst for some insurance company just trying to make it to the office. If he uses the capability of the vehicle ever, it is to move the boat from storage to the marina in the spring and haul it back to storage in the fall, something he could hire done for 1/100th of the cost of the Suburban. The number of these vehicles that are actually used to capacity is very small compared to the number sold. When they are, they are usually white and not "Amber Mist" and they have vinyl seats not leather and the come with an AM/FM radio not an eight channel sound system with dual sub-woofers. And they don't have $8000 worth of wheels and tires on them.
Back in the day, when I still had a strong back and worked putting up grain silos in eastern Montana, the company had a big, brown, 4 door, F350. When this thing went anywhere, it was loaded with a dozen large steel jack supports, a generator, a pile of electric impact tools, about 40 gallons of ice water, 4 or 5 workers and towing a trailer that had a big hydraulic pumping system with a dozen 4 foot long cylinders and about 400 feet of hose. This thing deserved to get 10 miles to the gallon, it provided value when it went anywhere. They also had a little Ford Courier that was used when only one or two people needed to go someplace or something small needed to be moved. While this thing didn't get anywhere near 50 mpg, it got way over 10. If they could have gotten a 50 mpg vehicle that would have held up to country roads in the mid 70's, they would have gotten one in a heart beat, because even though gas was under $1 per gallon, it would have paid off quickly because they racked up LOTS of miles. Eastern Montana is a big place and nothing is near anything else when you get out where they grow wheat.
Yes, context does matter. If you see someone who actually needs such a vehicle driving a Hummer, you have dropped into an alternate universe because it doesn't happen in real life.
But when I bought my last car, I looked squarely at the L/100km measurement. I did the math. And I realized that for what I'd save in the ticket price between buying a 2007 Chev. Aveo (which I did end up buying) over buying something like a Smart car or a hybrid, I could pay for the total gas I'd use over the entire lifetime of the car. The difference between 6L/100km and 3.8L/100km just isn't *that* significant, and certainly isn't significant enough to justify spending another $15,000 on a car that probably won't see 100,000km in its entire 5 year lifetime before I trade it in for a new one. The price of gas would have to be 7x what it currently is for that to have become an economical proposition.
The choice for an Hybrid or a fuel efficient car should not only take in to account the cost of the fuel, but also the cost to the environment. If you add the cost of a "carbon fee" for the extra fuel you burn, for the energy required to bring that fuel to you, the damage to the environment to extract that fuel, you get quite a good deal...
..ahhh England where I buy fuel in litres, put it in a car rated in mpg, drive in miles down the road, under a bridge measured in meters, go to the shops and buy a litre of milk, go to the pub and buy a pint of beer ....
Metric or Imperial .... we use both ....!
Puteulanus fenestra mortis