Your car goes 3.5 m.p.h.?

John Michael Greer, the Grand Archdruid of the Ancient Order of Druids in America, publishes a weekly post at his site, The Archdruid Report. Greer is a much deeper thinker than I, particularly with respect to the interplay between past, present, and future. He describes his area of thought as the "history of ideas," and his grasp is broad and deep, regardless of whether you agree with him or not. A steady diet of The Archdruid Report would certainly depress me, though Greer does not strike me as depressed. He's certainly "cocksure" though, in the sense of certainty of his conclusions.

Nevertheless, I read his posts from time to time and invariably find them thought provoking. Today, in reading his post entitled "Peak Meaninglessness," I found him citing Ivan Illich from "Energy and Equity" (available as a free pdf download) contending that

"Illich’s discussion focused on automobiles; he pointed out that if you take the distance traveled by the average American auto in a year, and divide that by the total amount of time spent earning the money to pay for the auto, fuel, maintenance, insurance, etc., plus all the other time eaten up by tending to the auto in various ways, the average American car goes about 3.5 miles an hour: about the same pace, that is, that an ordinary human being can walk."

Is it true? If it is, does it have any meaning? Since, for reasons that should be obvious, I'm not interested in using my personal financial details for such a calculation, I'll posit an American household earning the median income of $52,000/year. The household consists of a husband, wife, and two children. The husband works 2,000 hours/year and earns $40,000 and the wife works 1,000 hours/year and earns $12,000. As an aside, this family doesn't live in Southern California. The average hourly earning is thus about $17.30/hour. Of course they'll only bring home, at best, perhaps $14/hour after taxes.

I'll assume two cars traveling a total of 26,000 miles per year with an average of 1.2 people in the vehicle for 31,200 passenger miles per year. The vehicles average 25 m.p.g. and gas costs $3.80/gallon, so they spend about $3,950/year on gas.

One car is a relatively new (say, two years old and purchased for $29,000 on a five year loan at 5% API with 20% down) five passenger sedan. The monthly payment is around $440, or $5,280/year. The other is a minivan on a three year lease with monthly $3,000 at signing and $300/month lease payments, or $3,600/year. They paid $8,800 up front to have the vehicles but, since interest rates on money market investments are close to zero, the opportunity costs are quite low, so I'll use the up front cash divided by the respective term in months. This adds about $2,160 to the annual total. The total to finance the cars is $11,040/year.

They take the vehicles in for scheduled maintenance a total of eight times per year and spend $300 each time (sometimes less, sometimes more depending on the service required by the schedule). The total is $2,400/year.

This family has decent driving records and no teen drivers so the annual insurance premium is about $1,500.

The grand total (leaving out car washes, aftermarket accessories, etc.) of annual expenses is $18,890. Wow, that IS a lot of money! Now, this $18,890 takes 1,350 hours (45% of their working hours) of this family's time to earn. So the final result is in: 26,000 miles/1,350 hours is about 19.25 miles per hour. This is about 5.5 times faster than Illich's estimate. So the answer to the first question, "is it true?", appears to be "no."

The second question is not so easily answered. The entirety of this family's lifestyle revolves around the vehicles. Without them, it's unlikely (though certainly not impossible) that the $52,000 would be earned. And, while a vehicle undoubtedly constrains them financially, it also enables them to do many things that would otherwise be difficult or impossible. A vehicle-free lifestyle is certainly possible (I've lived such a lifestyle at various times and for various reasons), but this family has decided that the tradeoff is worth it. I WILL say, however, that they'd have been much better off with different vehicle choices. Another way of saying this is that I believe I've made assumptions that are generous to Illich's claim as repeated by Greer.

Elio Motors proposes an 84 m.p.g. "car"

The Elio Motors three wheeler is a design by Paul Elio that is expected to achieve a highway fuel economy of 84 m.p.g. (and a city fuel economy of 49 m.p.g.). The vehicle is expected to be on sale in 2015 at a price of $6,800. The price includes air conditioning, power windows, power door lock, AM/FM stereo, "and more." It's expected to have a 5 Star Crash Test Rating (the Elio has a reinforced roll cage, antilock brake system, stability control, airbags, and is made from carbon fiber composite).

It's not actually a "car" in the sense that we commonly think of them, it's a three wheeled vehicle. It seats two in a tandem configuration. For most states, that means that the Elio is regulated as a motorcycle (and in some states, a helmet will be required as things stand now). Pre-orders for the vehicle (with deposit) are said to be at 12,000, and Paul Elio believes that he can sell 250,000 Elios per year.

I can think of several applications where such a vehicle could excel. For example, I drive to work alone nearly every day and, in fact, well over 90% of the miles I drive my Lexus CT 200h are solo. I ran a quick check and the Elio would reduce my 400 gallons per year to 322 gallons for a savings of something like $312. Were I buying a new car, such a choice might be attractive at the $6,800 price point.

The Elio would likely also be a good candidate for a second vehicle for grocery shopping and other errands in a soccer mom family with the requisite minivan or SUV.

What about taxis? Here it's not so clear. The only door is to the driver's left and the rear seat is, charitably speaking, not optimized for the passenger experience (not to say claustrophobia inducing). And much taxi driving is in cities, where the Elio doesn't do any better than a Prius hybrid (and lots of my taxi rides recently have been in Priuses).

Fleet vehicles? Possibly, it certainly depends on the fleet and its intended use. What about for rental agencies? Here I'm also not so sure. I don't put a lot of miles on my rental cars when I'm out of town, I'm not so sure that I'm atypical. Thus, the fuel economy might not be particularly attractive. On the other hand, if the rental agency were to reduce the rental charge in proportion to the acquisition price of the Elio, we might have a deal.

Elio has a variety of fascinating financing options, the best article on those that I've seen is at this article in "the truth about cars" web site. The basis is that you get a credit card whose balance is the remainder of what you owe on the car after your deposit/trade in credit. You make payments on the card and when you purchase gas, you're billed for three times the gasoline cost. The difference between that price and the actual cost is used to pay down the car loan balance. The theory is that you're getting three times the fuel economy so you get the new Elio without paying anything beyond what you're used to paying for fuel for your (presumably) old, inefficient vehicle.

Now, one could say that the Volt, the Leaf, etc. do better than the Elio with respect to fuel cost (be they gallons or kilowatt hours) and one would be right. And those are four seat, four wheel vehicles. But, for the price of a Volt or a Leaf, one could buy an Elio and have some $30K left over. And it would certainly seem to be strong competition for the two seat Smart Car.

What about the mileage claim? The vehicle weighs about 1,000 pounds and sports a 70 horsepower, three cylinder engine. It doesn't look to be an aerodynamically smooth vehicle, but aerodynamics can be extremely deceiving. I can find no figures on drag coefficient or frontal area. But such trifles haven't stopped me before, so I'm going to plug and chug to see what results.

I'll assume a weight with driver of 1,170 pounds, a C_d of 0.32 (purely a guess, and one that I think favors the vehicle), tire rolling resistance coefficient of 0.0085 (assuming that Elio will go with low rolling resistance tires), an efficiency for the internal combustion engine of 30%, a frontal area of 2.3 m² and a highway speed of 60 m.p.h. Running this in my little Mathematica model of vehicle fuel economy yields an estimate of 67 m.p.g., 17 m.p.g. below Elio's claim. I think I've been generous with respect to engine efficiency, so the likely areas where I've "cheated" the Elio would be drag coefficient and frontal area. Frankly, I think I've been pretty generous here as well, so I'll be very surprised if the typical driver* achieves 84 m.p.g.

Finally, I have to apologize for the lack of posts in the last nearly three months. As my karate instructor made us say when he asked us why we made some mistake in form or execution, "NO EXCUSE SIR!"

*Driving at 55 m.p.h. as I do yields an estimate of 78 m.p.g.

The (probably) last post on regenerative braking

I've posted a couple of times on regenerative braking in my CT200h. This will, I expect, be the last. In the previous post I estimated that regenerative braking on a trip saved me about 5.9% of the gasoline I'd have used without it. I decided that a better test would be a full tank, so I monitored all of the regenerated watt hours for my most recent tank. Since it's kind of a pain in the rear, I'm not going to keep it up.

Calculating in a more efficient way than the very detailed way in the previous post, the results are as follows:

• The measured economy by miles divided by gallons at fill-up: 50.60
• The calculated economy without regenerative braking: 47.55
• Gallons per 100 miles: 1.976
• Gallons per 100 miles without regenerative braking: 2.103
• Per cent fuel savings: 6.04%

Not much different, so I think that it's safe to say that regenerative braking saves about 6% of the fuel I'd otherwise use.

I'm a bit surprised that the number is that low. In this post I discussed some of the factors that make hybrids so much more fuel efficient than their non-hybrid cousins and the regenerative braking was one of the factors I considered most important.

There is no non-hybrid CT with which to compare the fuel economy. I went to the DOE fuel economy site for the Camry (the four cylinder version)  and for the Camry hybrid. Using the combined highway and city estimates for each (28 m.p.g. and 41 m.p.g. respectively) it looks like the hybrid, per the government's test protocol, will use about 31.7% less fuel over any distance. It's reasonable to infer that, while the regenerative braking is a significant fuel saver, other factors (operating more frequently on more efficient areas of the engine map, capturing energy while coasting, automatic engine shut-off where appropriate, etc.) are at least as important.

More on fuel saved by regenerative braking

I published a post regarding how much energy is captured in the regenerative braking system in my Lexus CT200h hybrid. After some discussion with commenter Gabriel Grosskopf, I estimated that about 59% of the energy available (after subtracting the energy used to overcome aerodynamic drag, rolling resistance, and internal friction) was recaptured and used to charge the battery.

Since I (and others) have represented that the regenerative braking system is among the key reasons that hybrids achieve superior fuel economy, I decided to check the actual impact.

My round trip commute, generally downhill in the morning and uphill in the evening, is 62.46 miles and, for the last 10 fill ups, my average m.p.g. has been 52.47. So, to make my commute, I use, on average 62.46/52.47=1.190 gallons of gasoline. My display showed me today that my regenerative braking system added 700 watt hours or 2,520,000 joules to my battery that I could use for accelerating, hill climbing, etc. If I assume my electric motor is 90% efficient, I put 2,268,000 of these joules to work.

A gallon of gasoline (reformulated blend in this case) has an energy upon oxidation of 111,836 btu or 117,993,000 joules. I estimate that my internal combustion engine is about 25% efficient, so I put about 29,498,000 of these joules to work. My 1.19 gallons thus provide 35,103,000 joules that propel my vehicle (the remainder being lost as waste heat in myriad ways).

If I assume that I used all of the energy my brakes provided, then 35,103,000 + 2,268,000 = 37,371,000 joules of work were done to propel my car. Then, dividing by 0.25, I can estimate that 149,484,000 joules of oxidized gasoline would have been necessary to do this work. This is the energy in 1.267 gallons. Dividing this into 62.46, I find that the fuel economy without the regenerative braking would have been about 49.30 m.p.g. The regenerative braking thus upped my m.p.g. by 3.17.

As I've often said, it's much more intuitively informative to discuss gallons per mile, or gallons per 100 miles. So, the regenerative braking took me from 2.03 gallons per 100 miles to 1.91 gallons per 100 miles. So it takes me 5.9% less fuel to go a given distance, ceteris parabus.

There's no question that I'm carrying a lot more significant figures (apologies to John Denker) than are warranted by the precision of my data, but I think that the figure I've determined is probably in the ballpark.

Low hanging fruit revisited

Photo credit: Lincolnloop.com

About three years ago, I posted an article on the "low hanging fruit" in fuel savings. In that article, I demonstrated that for a given increase in m.p.g., the lower the starting m.p.g. (before the increase) the more fuel will be saved by that increase. Thus, a driver who drives 12,000 miles per year and increases from 15 m.p.g. to 18 m.p.g., either by purchasing a new vehicle or changing driving habits, will save about 133 gallons of gasoline per year. Another 12,000 miles per year driver who increases from 25 m.p.g. to 28 m.p.g. will save only about 51 gallons per year. The best way to understand this is to think of gallons per mile or, more transparently, gallons per 100 miles, the inverse of m.p.g. This number is 100*1/(m.p.g.) Thus, the first driver uses 6.67 gallons per 100 miles before the change and 5.56 gallons per 100 miles after. This driver saves 1.11 gallons every 100 miles. The second uses 4 gallons per 100 miles before and 3.57 after. This driver saves 0.43 gallons every 100 miles.

I was reminded of that post by this article in Energy Trends Insider. The article discusses a construct from the Department of Energy (DOE) at a new website that discusses the so-called "eGallon." This number purports to give the quantity (or cost) of the electricity that it would take to move a "typical" electric vehicle (EV) as far as a gallon of gasoline takes an "average" conventional car. This is where the "low hanging fruit" concept comes in. Replacing a 20 m.p.g. vehicle with an EV saves MUCH more than replacing a 30 m.p.g. vehicle. The 30 m.p.g. vehicle goes half again as far on a gallon and thus the eGallon costs more for that driver.

I applaud the DOE for attempting to clarify the possible savings in fuel expenditure vs. electricity expenditure but, in some cases, it may be very misleading. The calculation is further complicated by the wide variance in how electricity is priced in various localities.

As to the "low hanging fruit," the plot below shows, for a driver who drives 12,000 miles per year, how many gallons of fuel are saved per year by moving from one m.p.g. driving regime to a higher one. It plots initial m.p.g. from 10 to 40 and final m.p.g. from whatever was the initial m.p.g. to 120 m.p.g.  The "front" axis is initial m.p.g., the axis that extends back and right is final m.p.g., and the vertical axis is gallons saved. As can be seen in the rightmost portion, the savings from a high starting point are not nearly as large. It's also easy to see, especially at the left end, that the big gains are in the initial improvements - the slope is dramatically steeper than at the higher final numbers.