Another couple of supposed “facts” from our company fitness center. Good thing they call them “factoids” because it’s hard to imagine where they come up with this stuff.
First: “The tongue is the strongest muscle.”
This seems to be the subject of great debate amongst purveyors of psuedo-science throughout the internet. I have to agree with those who declare simply that it is hard to imagine any objective criteria that would lead to the tongue being identified as the strongest. Wikipedia has a rather nice (if un-cited) list of potential strongest muscles using various criteria. Some say it is the strongest by size, but it’s not clear how one would measure this… ever try lifting a weight with your tongue? This useless answer on “wiki-answers” posits that your tongue will win a ‘finger war’ with your pinky… which of course must prove it is stronger than ANY other muscle. Oh… and for what it’s worth, my pinky wins.
Second: “Every 5mph over 60 is like paying an extra 10 cents per gallon for gas.”
This at least SEEMS plausible, but it certainly seems to be WAY to general. I would expect this to be a strong function of the efficiency of the car, the gearing, the aerodynamic properties, the base inefficiency of the vehicle (non aerodynamic losses) not to mention… THE PRICE OF GAS.
At www.fueleconomy.gov (yes there is one), the result is slightly different:
Observe the Speed Limit
While each vehicle reaches its optimal fuel economy at a different speed (or range of speeds), gas mileage usually decreases rapidly at speeds above 60 mph.
You can assume that each 5 mph you drive over 60 mph is like paying an additional $0.26 per gallon for gas.
Observing the speed limit is also safer.
Well that settles it for me!
What, you want some other opinions?
- EarthFirst.Com quotes: “Each 5 mph you drive over 60 is like paying an extra $0.30 per gallon for gas.”
- The Department of Energy quotes: “Each 5 mph you drive over 60 mph is like paying an additional $0.15 per gallon for gas.”
- US New & World Report quotes the EPA as saying: “According to the EPA, each 5 mph over 60 that you drive decreases fuel efficiency by up to seven percent.”
- NPR quotes the EPA as saying: “Assume that for every 5 mph you drive over 60 mph, you might as well be paying an additional $0.20 per gallon for gas.”
That definitely settles it! We need to do some math.
Q: What change in efficiency is required to cost an extra 10 cents per gallon of gas?
A: Here we go…
First we have to define the question, I choose to interpret it as meaning that you need 10 cents more gas to go the same distance that the gallon would have taken you otherwise. What’s amusing about this, is that the more gas costs, the less impressive this is. I suspect this is the primary reason we so many figures above. Let’s assume this statistic was written when gas was selling for a mere $1 per gallon (as recently as only 8-10 years ago). This makes the math easy, clearly if $1.10 of gas only goes as far as $1.00 of gas, then we’re burning 10% more gas per mile traveled [1]
5 years later when gas was around the $2/gallon mark, the ratio becomes $2.10/$2.00 for only 5% extra gas. Obviously at the current (or recent) $4/gallon mark, this is reduced to a mere 2.5% change. To align with the USN&WR statistic of 7%, gas would need to sell for…
0.1/x = 0.07
0.1 = 0.07x
x = 0.1/0.07 = $1.43 per gallon.
Regardless of the percentage, it is clear that increasing speed will dominate the (controllable) loss terms very quickly indeed. That whole “v squared” term in the aerodynamic drag model tends to hose you in a hurry (HA!). However, 10 cents extra per gallon is in the noise at $3.799 per gallon.
Oh… and when are they going to drop the stupid nine-thousands of a dollar business? Given that it is now less than a quarter of a percent change in gas price (and the price changes more than that every day), you’d think we could stop the silliness.
- Yes! Gallons per mile is a MUCH more useful statistic than miles per gallon. I’ll save that for another blog post. [↩]
September 25th, 2008 at 11:54 am
What? You don’t like paying $3.539 for your gas? You want it rounded up to $3.54? Silly boy.
With my 17 mile one-way commute, 180 days of school per year (plus or minus inservice days) in my 20 mpg van, that would cost me another 30.6 cents per year. You madman!
September 25th, 2008 at 11:55 am
And … think of the irreparable harm it would to to the big-plastic-numbers-for-gas station-signs industry if they no long had to produce those tiny 9s.
September 25th, 2008 at 6:33 pm
Actually, the impact on the sign makers themselves, since many of the 9’s are on the permanent part of the sign itself.
September 26th, 2008 at 6:07 am
Don’t worry, when we hit ten bucks a gallon they can just shift the decimal point and everything will work itself out.
September 26th, 2008 at 6:12 am
Regards to price per gallon … I’m glad cars don’t run on milk. I paid nearly $4.50 for a gallon yesterday. My family now goes through 3-4 gallons a week. Yowza.