Can you solve Seth Godin's math problem?

If we americans worked in gallons/mile instead these sorts of decisions would be obvious and intuitive. No one goes out with the goal of burning a gallon of gas so measuring how many miles you can go by burning one is silly. mpg is the reciprocal of what they want and people are bad at reciprocals.<p>I fixed his problem below:<p><pre><code> Suburbans: 23.5 liter/100km Priuseses: 4.7 liter/100km Suburban+: 18.0 liter/100km (save 5.5 liters) PriusPlus: 2.3 liter/100lm (save 2.4 liters) Would you rather save, 5.5 liters or 2.4 liters? </code></pre> (And you don't have to "go metric", just using gallons/1000miles would do fine.)

The root of the problem is that we shouldn't be thinking in miles per gallon - we should be thinking in gallons per mile.<p>The follow-up problem is that average person think miles per gallon is linear (as they would phrase it, "the difference between 1MPG and 2MPG is the same as the difference between 60MPG and 61MPG") because they don't know any better, whereas it's really an inverse/reciprocal relationship.<p>I wrote a more though explanation of this - <a href="http://www.daniellanger.com/blog/2009/08/miles-per-gallon-vs-gallons-per-mile/" rel="nofollow">http://www.daniellanger.com/blog/2009/08/miles-per-gallon-vs...</a> - the last time MPG came up in discussion, when there was some minor outrage over the Volt claiming 230MPG.

The premise is flawed. We start with: <i>Let's say your goal is to reduce gasoline consumption.</i><p>And then we start talking about fuel efficiency. IIRC, though, it's pretty well established in the economics literature that increasing fuel efficiency doesn't reduce gas consumption much, if at all. Increased fuel efficiency means lower effective gas prices, which people respond to by driving more.<p>The net effect is about the same level of fuel consumption, with more cars on the road (i.e. more traffic and more accidents).<p>If you want to reduce gas consumption, you have to increase the price. Good ways of doing this include taxing it, increasing demand for other stuff made from petroleum, or reducing supply.

I find the easiest thing to do is assume we drive some distance, then work out how much gas is used.<p>If we drive 1300 miles the numbers all work out easily (because it's divisible by 10, 50 100 and 13)<p>Suburbans get 10 mpg: 130 gallons<p>Priuses get 50 mpg: 26 gallons.<p>Suburbans @ 13 mpg: 100 gallons (30 gallons improvement)<p>New Prius @ 100 mpg: 13 gallons (13 gallons improvement)<p>So clearly the best thing to do is scrap all the Suburbans and replace each with a newer style Prius.

This is a solved problem. Seth actually linked to my explanation of it. <a href="http://charliepark.tumblr.com/post/169016492/in-seth-godins-post-this-morning-he-talks-about" rel="nofollow">http://charliepark.tumblr.com/post/169016492/in-seth-godins-...</a>

That would only be a "math problem" if it came with enough numbers to do some calculations.<p>Oh, wait -- he's probably assuming that the only worthwhile metric in the problem is fuel usage. Well, with <i>that</i> requirement, it's easy. Hell, I've even done the calculations for determining how long it would take to recoup my losses if I bought a motorcycle and used that instead of a car with decent fuel efficiency, given some assumptions about future gas prices, a while ago:<p><a href="http://sob.apotheon.org/?p=449" rel="nofollow">http://sob.apotheon.org/?p=449</a>

Here's a better solution: replace the suburbans with Priuses instead of buying into Godin's tired, second-hand false dichotomy. Some of us are wired for arithmetic, actually.

It may look unintuitive, but it's just an optimmization problem. When you optimize, you always begin with the most resource-intensive element, because that's where most of the gains are.

If the goal is to reduce gasoline consumption I'd suggest<p><pre><code> * banning futures trading on oil world-wide. * provide free public transportation.</code></pre>

m/10 - m/13 &#62; m/50 - m/100