Can you solve Seth Godin's math problem?
sethgodin.typepad.com
sethgodin.typepad.com
I fixed his problem below:
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?
I tend to think that one of the reasons that Americans tend to have less fuel efficient cars is that when they are evaluating alternatives 9 mpg and 10 mpg are "closer" or more equivalent than 47 mpg and 50 mpg. For example, if I go out and buy a Truck in Canada I could either compare
Ford F150: 15.7 liters/100km (15 mpg) city, 11.2 liters/100km (21 mpg) highway.
GMC Sierra 2500 4WD: 14.7 liters/100km (16 mpg) city, 11.76 liters/100km (20 mpg) highway.
With the Sierra, you are using a full liter less of gas during city driving at the cost of only half a liter of highway driving, so unless I'm doing more than 66% of my driving on highway like conditions, I should go with the Sierra, but that information does not come across to gas conscious buyers that use mpg.
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.
I wrote a more though explanation of this - http://www.daniellanger.com/blog/2009/08/miles-per-gallon-vs... - the last time MPG came up in discussion, when there was some minor outrage over the Volt claiming 230MPG.
The average person is pretty bad at dealing with fractions, too. Are they going to get the difference between 0.05 gpm and 0.04 gpm? Seems pretty small, it's just 0.01!
Another interesting argument, although I can't find a source offhand, was to force manufacturers to display a gallons/10,000mi - on the basis that since the average American drives something like 10Kmi per year, this would convey much more concretely the longer-term difference between fuel consumption.
Personally, I like MPG because it makes the range-on-a-tank-of-fuel calculation much easier, and I care much more about range than about fuel economy.
I was sad when it turned out the original Honda Insight didn't get 70MPG, because, otherwise, it would have been interesting due to the 700 mile range.
If we're talking about serious off-road vehicles, then I can see why you'd want to max out your range to make trip planning easier. But thinking of the majority of drivers doing the majority of their driving (especially in cars like a Honda Insight), they'd be hard-pressed to end up going somewhere that didn't have a gas station at least every 200 miles.
The way I do it is that I know my work commute is about 30KM, so about 150KM per week, and that my Mazda has an average combined fuel efficiency of about 7L/100KM - meaning that my commute uses about 42L of fuel per month. I know that gas costs around $0.96/L in this area at this time of year, so my commuting costs about $40 per month in fuel.
I use this line in my budget, and hence pay less attention to exactly when I refill my tank - and know that any amounts I spend on gas above this number are somewhat discretionary.
The first is commuting. Filling up takes an extra 5-10 minutes above and beyond the fuel dispensing time (assuming that's linear, which, with my CNG car, it isn't, but that's another topic). A car with a 450 mile range over one with a 225 mile range would save me 4-8 hours per year.
The second is pleasure travel. Sure, the nearest fueling facility may be under 50 miles away, but it may easily be 10-30% more expensive than a farther one, especially across a tax jurisdiction border (especially Canada/US). At $3/G and 60G for a 2000 mile round trip, I'd prefer to keep the Andy Jackson or Uly Grant (Common Loon or Snowy Owl on the reverse if North of the border) or spend the money on an unplanned couple hundred miles' detour.
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.
The net effect is about the same level of fuel consumption, with more cars on the road (i.e. more traffic and more accidents).
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.
Figure out how to make it affordable (while being safe) for people to live closer into major cities, and you'll have a real impact on gasoline usage.
For example, my own driving is not money-limited-- gas could double in price and I would drive just as much, because I drive so little already. Whether I pay $200/year or $400/year for gas doesn't make a difference.
I suspect that the vast majority of miles driven are driven by people who would find cheaper alternatives, like buses or bicycles or email, if prices went up even 20%. But that's just speculation. Empirically, when gas costs doubled briefly last year, it seemed to me that traffic was still almost as bad.
So, I mostly agree with you, but I'm not 100% convinced.
Yes, but (I infer that) you're a well-paid, environmentally-conscious professional living in the center of a dense (and expensive) city. For everybody like you, there's a pizza delivery driver on the other side of the bell curve who covers 200 miles a night. If delivery-miles get cheaper, we have no reason to think the pizzeria wouldn't spend the savings on more drivers, so as to reduce the amount of time customers have to wait.
when gas costs doubled briefly last year...
We wouldn't expect to see much change so soon after the price shock. Filling up at $4.50/gallon is no fun, but in the short term it's something people are willing to put up with rather than buying a new Prius or moving into a new home with a shorter commute.
If we drive 1300 miles the numbers all work out easily (because it's divisible by 10, 50 100 and 13)
Suburbans get 10 mpg: 130 gallons
Priuses get 50 mpg: 26 gallons.
Suburbans @ 13 mpg: 100 gallons (30 gallons improvement)
New Prius @ 100 mpg: 13 gallons (13 gallons improvement)
So clearly the best thing to do is scrap all the Suburbans and replace each with a newer style Prius.
Oh, wait -- he's probably assuming that the only worthwhile metric in the problem is fuel usage. Well, with that 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:
* banning futures trading on oil world-wide.
* provide free public transportation.