something to think about when you are considering a new car or truck...
Why MPG is a stupid measurement
Originally posted by Hank Green http://shine.yahoo.com/green/We tend to have bad measurement systems here in the U.S. We've got a temperature scale where water freezes at 32 degrees and boils at 212 (it's zero and 100 for the rest of the world). And none of our measurements are compatible with our base10 numbering system. Twelve inches in a foot? 5,280 feet in a mile? I mean, come on...
So it should come as no surprise that measuring vehicle efficiency in miles per gallon is about as effective as measuring a city's population density in square miles per person.
The reason is simple. What we want to know is how many gallons we'll save, but what we're getting is how many miles we can go. This might seem like a small difference, but displaying miles per gallon in gallons per mile immediately shows some huge flaws in our current system:
15 mpg = 660 gallons per 10,000 miles
20 mpg = 500 gallons per 10,000 miles
30 mpg = 330 gallons per 10,000 miles
45 mpg = 220 gallons per 10,000 miles
60 mpg = 160 gallons per 10,000 miles
Now, obviously, the most fuel-efficient car here is still the 60 mpg car. And that's fantastic. But increasing the mileage of a 15 mpg car to 20 mpg, saves as much gasoline (and carbon) as doubling the mileage of a 30 mpg car to 60 mpg.
But to the consumer's eye, the difference from 15 to 20 might not seem all that important. One might even go so far as to say that consumers would see it as insignificant. If they're going to buy an inefficient car, what does it matter if they get an extra five miles for every one gallon of gas?
This, in short, is why the Chevy Tahoe Hybrid won Green Car of the Year this year. And while it may seem like the best way to save gas is to make small cars more and more efficient, it's obviously much more important to work on the big cars first.
Not only is a gallons-per-10,000-mile system more accurate in terms of efficiency, it's better for consumers. It shows them exactly how many gallons they'll be burning. And, from there, it's only a quick multiplication to get yourself a big scary number for your gas bills.
Of course, if history is any guide, switching the units will be no easy task. But the next time you're at a dealership, maybe you should bust out your calculator and figure out how many gallons per mile you'll be getting.
Please send questions and comments to GDempsey@fortlauderdale.gov