Observations on a Hybrid Vehicle

by Oliver Seely

The text and photos on this page are in the public domain. Copying is encouraged!

Revised March 5, 2006

Most automobile owners purchase a car according to the rule that one size will have to fit all needs. This usually translates to mean a car the size of which will satisfy the most demanding requirement. To that end in 1994 my wife and I purchased a sports utility vehicle big enough to pull our tent trailer.

It has served us very well. When the photo at the right was taken it had gone a distance exceeding 120,000 miles (192,000 km) and it is still going strong. Except for summer camping trips, I commuted to work, 8 miles (13 km) each way, five days per week, 10 months per year in this large car. One person in a behemoth getting 17 miles per gallon (7.2 km / liter) to go from point A to point B and back again.

Knowing that it wasn't going to last forever, that gasoline prices were on the rise and that I had always wanted to drive a "sensible" car, I purchased a hybrid. My mileage shot up to around 52 miles per gallon (22 km/Liter). European readers of this page are liable to laugh at this because many of them are already getting better economy in cars solely with internal combustion engines, but that's another story.

I've had my hybrid for just over one year, long enough to report on some interesting observations about the performance of this sensible car. It soon became clear that my increased mileage was more the result of a smaller engine (1.3 liters vs. 4.0 liters for the SUV) than because of any advanced technology, but the hybrid does have several features which deserve some comment. The first is that because of a battery which pushes the car along when traveling under 20 miles per hour (32 km/hr), one's emissions when driving in congested traffic are greatly reduced. Secondly, an engine operating within its normal temperature range turns off when one stops at a traffic light. The electric engine doesn't continue to run, either. The joy of knowing that one isn't consuming fuel while the light is red turns to irritation when at the wheel of the SUV under similar circumstances.

The third and most radical of new features on my hybrid is "the screen" which offers me a series of histograms on economy. The ones at the left show my average mileage in five minute increments and the one at the right shows my instantaneous mileage. Sorry for the blurry rendition, but my wife wasn't always handy to take pictures for me.

The image on the left shows my average mileage from a cold start. Even with the most prudent driving, I can't get much over 25 mpg during the first five minutes. The second five shows a mileage which approaches one's overall average. Occasionally one takes a route which offers some very easy, constant and level or perhaps downhill driving during the second five minutes. Such was the case with the image below right, in which the first five minutes was around 25 mpg and the second shot all the way up to over 100 mpg. What goes up must come down, inevitably, and the third five minutes dropped below my average of around 52 mpg.

The image at the left, a repeat of an earlier one shows what happens when accelerating under any circumstances: cold or hot. The realization that one's mileage plummets on acceleration and particularly when one's engine is cold is a revelation which has a lasting effect. It argues strongly that if one's use of an automobile is for many short trips during the day, a purely electric vehicle is the way to go. Moreover, the availability of the screen leaves one convinced that the advancement here is not the hybrid technology but a screen telling you how you're doing as you drive - that prudent pressure on the accelerator can markedly increase one's mileage. Without it we don't know, exactly, how we're doing. We may know, as something of an abstraction, that frequent acceleration lowers one's overall mileage, but that realization doesn't motivate us to change our habits every time we fill up. The experience is not unlike the sumptuous and romantic evening meal with wine and dessert and the stark reality brought to us while standing on the bathroom scale the next morning.

One amusing advantage of having the screen in front of you is the realization that the way to push your mileage through the roof is to drive the freeway at rush hour behind an 18-wheeler between 11 and 30 miles per hour as in the image on the right. Keep enough space between you and the rig so that you never have to step on the brake. Buffer your distance with a lot of coasting. The driver of the rig sits high enough to know what is up ahead. He too avoids having to brake frequently. So both of you mosey along enjoying the scenery, as opposed to everyone else hell-bent to get to their stunningly interesting jobs, or an evening of couch potato existentialism.

Look at that instantaneous mileage: more than 100 mpg! Drivers behind you won't get impatient because they'll think you're just a timid soul who doesn't want to accelerate to pass the rig or perhaps that you're patiently waiting to arrive at the next exit. They won't have a clue that you're exercising a driving strategy.

Even a short commute allows one to get phenomenal mileage, though not if you are in a hurry. The image at the left shows an almost ideal situation of an 8-mile commute where the first five minutes gave low mileage while the engine was warming up (though even here, the traffic was conducive to allowing me to poke along and to maximize the allowable mileage). The freeway was jammed and moving at between 10 and 30 mph. The outside temperature was around 75 degrees F. On a generally level route under these conditions each succeeding 5-minute interval gave between 60 and 70 mpg.

Of course, your electric motor finally stops pushing you because the battery falls to half charge and your internal combustion engine comes on to charge it. But the charging operation is done very prudently - no quick acceleration, no taxing of the engine. Depending on driving conditions, your mileage may drop to around 30 mpg (see below, right). This strategy is clearly not meant to be exercised if you're in a hurry.

The American magazine "Consumer Reports" gave a mileage rating to this hybrid of around 41 mpg. For driving with the air conditioner on and with no attention paid to the screen reading I find that to be about right. But with the air conditioner turned off and lots of attention paid to one's instantaneous mileage, one can easily maintain over 50 mpg during the summer months and 43+ mpg during the winter. The claim by the manufacturer of 566 miles per tank of gasoline is not an exaggeration either. My top distance for one tank of gasoline is 593 miles and I'm sure that I could have topped 600. A recent program on the History Channel on the subject of "The History of Engines" pointed out that mileage enjoyed by hybrids depends very much on "how they're driven." But that is true of all cars.

In looking through the Web on the compound keyword "mobil economy run" of the 70 or so hits one gets it isn't easy to find actual winning mileages. One gets statements of "1st in its class" or "winner of the 19xy Mobil Economy Run" but one doesn't often find the actual mileages. Here are two which did pop up at me.

"During the 1962 Mobil Economy Run, a stick-shift AMC Rambler with the same engine as our test car (except that it was the 125-hp version with single-throat carburetor) delivered 31.11 mpg"

"1965 Imp in the Canadian BP Economy Run Lowest Consumption of any competitor with 46.34 mpg"

I remember as a youngster marveling at the high mileages achieved by drivers on cars which for the rest of us were performing only half as well. It was well known that the drivers were highly trained to drive in a manner which minimized acceleration and moved at speeds which minimized air resistance and inefficient fuel consumption. Read "driving as though one had a screen to look at."

With that screen, one can often pull off averages as shown in the image on the left though even here, the necessity of accelerating and driving in mountainous areas can get in the way of top mileage.

The July, 2003 issue of Popular Mechanics ran an article comparing the Honda Civic Hybrid and the Honda Civic EX gas powered cars. Even though the hybrid costs only $1440 more than the gas-powered version, PM concluded "All said and done, if you were driving the same route, at the same speeds, in the same conditions, it would take roughly 144,000 miles before the Hybrid paid back its $1440 premium over the Civic EX."

The image at the right shows an interesting progression of mileages. The November temperature was a little cooler than the hottest part of July, as you can see and I left work after the sun went down so the headlights were pulling more current from the battery than the running lights which are always on. The first five minutes show the standard "cold engine" mileage of around 25 mpg. My route home goes up a slight incline and then starts gently down for about a mile. The second five-minute mileage exceeds 75 mpg but reflects some stops and accelerations at traffic lights. The third five minutes hits the upper limit thanks to the continuing decline. The fourth five-minute mileage reflects level and slow freeway travel at rush hour but with some loss due to my having accelerated along the on-ramp. The advantage in mileage offered by the electric motor comes to an end when the battery falls to half charge. The internal combustion engine comes on to charge the battery and I can't do anything about it. The mileage for that interval drops all the way back to around 30 mpg. The battery continues to be charged after I exit the freeway. Once fully charged and on level surface streets in our tract and able to poke along allowing the electric motor to push me, the mileage reaches 75 mpg in the last 5-minute increment.

Prudent driving on surface roads can offer mileage every bit as good as the one above. Here at the left is the mileage sequence on a trip from from Fresno Pacific University to the Corner Cafe in Clovis, a distance of 8.5 miles. Note that it took us 30 minutes to get there. The folks in Fresno and Clovis presumably haven't yet discovered how to keep traffic flowing through the synchronization of traffic lights. There was a lot of stop and go on the trip, but the region is about as flat as a dry lake bed and high mileage can be maintained, particularly considering that the outside temperature of 86 deg.F didn't force the engine to keep running interminably to keep it at an efficient operating temperature.

A constant speed on cruise control of 62 mph on a level highway produces a sequence of mileages just above 50 mpg as shown in the image to the left. The route was from Bakersfield to Fresno on the way to Yosemite National Park. On the return journey, south of Bakersfield, the elevation increases from sea level to just over 4000 feet at Tejon Pass. Note the slow decrease in mileage at this constant speed until during the last segment the Pass has been reached and the mileage begins to increase as the route descends into Los Angeles.

When I created this page five years ago I wasn't at all sure of the veracity of the first statement in the paragraph below so it was with more than a little satisfaction that I read in the April, 2006 issue of "Consumer Reports" of the conundrum faced by the person trying to decide between a hybrid and a conventional internal combustion engine automobile: ". . .hybrids are typically priced thousands of dollars higher than similar all-gas models" and "for people who believe that hybrids will also save them money, the picture hasn't been so clear."

Here's the statement about which I wasn't sure:

The bottom line, sadly, is that one is likely never to recover the extra cost of this automobile. If that concerns you, save the extra bucks and buy the model with the 1.5 liter internal combustion engine by itself. On the other hand, the screen is so very appealing. It certainly beats putting on makeup, playing solitaire, reading the newspaper or talking on your cell phone during a boring commute.

I would add, however, that because so much of our use of automobiles is for short trips, and after having owned a hybrid for more than 4 years and watching the mileage indicator stay just under 25 mpg for the first five minutes each morning while warming it up, I think there may be a great future for a hybrid vehicle with a larger battery which can be charged alternatively by the internal combustion engine or by plugging it in between trips and which can be driven much further on a battery charge than that which is allowed by current hybrids.

All that having been said, if I were truly civilized and enlightened I'd forget about this internal combustion/electric motor baloney, get a bicycle, commute between home and work and stay in excellent physical condition like Dr. Lyle. Here he is at the right starting one of his daily commutes from Hermosa Beach to our campus at CSU Dominguez Hills.

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