Filed under: MPG, AutoblogGreen Exclusive
Find out just how fast (or slow) to drive to work
AutoblogGreen reader Rhett left a comment on a post the other day about a just-for-fun fuel cost calculator he's built on his website. While Rhett says right off the bat that the calculator isn't perfect, and I thought it might be a good idea to get the ABG community involved for some helpful criticisms.
The idea is that the most cost-effective speed to drive your car needs to be based on your hourly earnings and your car's mpg. Factor in the cost of fuel and the speed at which your car gets the best mpg, and you have Rhett's optimal commuting speed calculator . Some of the problems with the calculator are due to the need to use old data. Also, super-efficient vehicles kind of blow the model out of the water. Rhett says there are improvements coming to the calculator, so feel free to chime in with those helpful hints.
[Source: Trivial Physics]
Reader Comments (Page 1 of 1)
mike 8:44PM (2/21/2008)
- Right off the bat it assumes that the higher your pay, the more your time is worth, and therefore you're "allowed" to speed. Time isn't money on the road. For safety, you should never be more then 10 mph faster then anyone else.
- If your so important you think you can justify speeding, you should have a chauffeur, and be chauffeured around.
So the "calculator" was built for the "a**holes" who make things more dangerous for everyone else.
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PJD 9:53PM (2/21/2008)
Take public transportation and get work done while you're commuting. Join a carpool and get work done... or enjoy the socializing.
Doesn't take a degree in optimization theory to work out the best solution.
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Mattias 3:28AM (2/22/2008)
This diagram nearly exactly represents my experience on german autobahns. Depending on congestion, the ideal speed seems to be between 75 and 80mph. At this speeds I get 45+ mpg. Going faster than 90mph faster only saves a fraction of the time and nearly proportionally increases consumption. At 8 or 9$ a gallon the negative effects are costly even with the economic diesel.
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rgseidl 12:50PM (2/22/2008)
In many places, e.g. LA or London, commuters achieve more like 20mph than 65 because of rush hour. As an individual, there isn't much you can do about that, so you're forced to suffer traffic jams. Moving closer to work or finding work closer to home is often not possible or at least difficult. Telecommuting is only possible for a select few.
Public transportation systems - especially light rail and subways - can greatly alleviate congestion, but only if they are clean, safe, reliable, operate frequently and connect sufficiently large areas. In many parts of the US, the car culture has led to low density in both residential and commercial districts, something that is extremely hard to reverse.
An alternative approach would be a rolling weekend. If enough employers decided to let half their staff work Tuesday-Saturday and the other Sunday-Thursday, congestion would be greatly eased four days out of every seven. Of course, running a business - or a family, for that matter - on that kind of schedule would be quite a challenge.
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Mattias 12:57PM (2/22/2008)
What speed limit? We should have one. I think 130 or 140km/h are enough. The limit could be loosened on autobahns with three or more lanes with an automatic traffic control system. Currently the situation is that when steadily going 130 to 140km/h (80mph to 85mph), many people consider you as an obstacle and try to go at 190mh/h (120mph) or faster, even if the congestion does not allow it. This sucks. It costs precious fuel, You do not arrive significantly earlier and it costs nerves.
BTW: I could go faster than 120mph but I'm on the autobahn for travelling and not for racing.
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MikeW 1:11PM (2/22/2008)
The 'speed limits' are not set by the 85-95th percentile of free flowing traffic, or by a civil engineer.
Usually the politicians lower the 'speed limit' for 'safety', which causes the problems.
Pigment on a piece of metal doesn't overrule common sense.
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Byron Thomas 5:49PM (2/22/2008)
I have no problems whatsoever with a driver going a bit fast, or driving a bigger gas hogging vehicle. As long as THEY PAY FOR THIER POLLUTION, and the interference, and the dangers caused to others by big SUV's (I can't see over or around an SUV in front of me) and fast cars. Of course, these people, and all of us, need to pass a more stringent driving test. Wouldn't that eliminate 10% of congestion right there, only allow skillful drivers on the road? I don't think going 25 in a 25 is a good test of skillful driving. Remember speed limits are set for "the lowest common denominator". PS: A $1 a gallon or more gas tax kinda takes care of all those issues....So you are 16 and just got a car? Ok, fine, $1gal extra tax. You are old, and can barely see and react? Ok $1 gallon tax. You are lazy or afraid of buses and mass transit? OK, $1 gallon tax.
You wanna live in modest green abode near work and shop locally? OK, walk or bike, there is no air pollution, no global warming, no war in Iraq, and you don't pay any tax. Seems fair to me, and every other modern country.
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RockStoneSteel 8:06PM (2/22/2008)
How about going the speed limit to prevent the traffic congestion caused by drivers going at different "optimum" speeds?
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