Driving a gas-guzzler? You can still cut fuel costs by nearly half

Sep 08, 2011
Driving a gas-guzzler? You can still cut fuel costs by nearly half

(PhysOrg.com) -- While driving a fuel-efficient vehicle is the best way to save gas, motorists can still cut fuel consumption nearly in half by driving slower and less aggressively, properly maintaining their vehicles and avoiding congested roads, say University of Michigan researchers.

"Driving a light-duty in the is currently more energy-intensive than using a bus or a train and even flying," said Michael Sivak, research professor at the U-M Transportation Research Institute. "How can we improve on this performance? Vehicle selection has by far the most dominant effect—the best vehicle currently available for sale in the United States is nine times more fuel-efficient than the worst vehicle.

"Nevertheless, remaining factors that a driver has control over can contribute, in total, to about a 45 percent reduction in the on-road per driver—a magnitude well worth emphasizing."

Sivak and colleague Brandon Schoettle studied the effects of decisions that drivers can make to influence on-road fuel economy of light-duty vehicles. These eco-driving practices include strategic decisions (vehicle selection and maintenance), tactical decisions (route selection and vehicle load) and operational decisions (driver behavior).

The UMTRI researchers say that choosing to drive a car (23.7 average mpg for model year 2011) rather than a minivan (19.4 mpg), SUV (19.2 mpg) or pickup truck (17.2 mpg) may be the easiest way to save gas. However, regardless of vehicle type, drivers who keep their engines tuned, tires properly inflated and use the right kind of engine oil can improve fuel economy by as much as 40 percent.

Further, by choosing to drive on routes that include highways, flat terrain and less congestion, motorists can save gas. For example, a flat route can yield 15-20 percent better fuel economy than a hilly route and taking a free-flowing highway route as opposed to a highly congested route can improve fuel economy for that trip by 20-40 percent, the researchers say. In addition, carrying extra cargo (e.g., an additional 100 pounds), can reduce fuel economy by up to 2 percent.

Finally, Sivak and Schoettle say that driver behavior can go a long way in improving fuel economy. Driving slower and less aggressively can save up to 30 percent in gas usage, while turning off the air conditioner can save up to 25 percent and using cruise control can save 7 percent while at highway speeds. In addition, letting a vehicle idle for more than a minute can significantly reduce fuel economy.

The actual fuel savings that good eco-driving practices will yield, however, are dependent on specific and sustained conditions. Consequently, according to Sivak and Schoettle, the actual total savings will be less than the sum of the listed maximum savings for each individual eco-driving practice.

By disregarding good eco-driving practices, drivers of the most fuel-efficient car with an internal-combustion engine (36 mpg) could see their fuel economy drop below 20 mpg—although this is still better than the least fuel-efficient car driven according to all good eco-driving practices, the researchers say.

"This can be interpreted as the cup being half full or half empty," Sivak said. "On one hand, one can conclude that decisions concerning vehicle-selection are dominant for on-road fuel economy. On the other hand, one can also conclude that following the remaining good eco-driving practices can still lead to a major reduction in on-road fuel economy."

The researchers say their analysis focused on fuel economy per vehicle, not per occupant. However, the average occupancy of a light-duty vehicle has dropped from 2.0 in 1960 to 1.4 today.

"This represents a 30-percent drop in vehicle fuel economy per occupant," Sivak said. "Consequently, increased carpooling, to at least the level of the 1960s, would go a long way to improve energy intensity of driving per occupant."

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More information: Complete Study (PDF): ECO-DRIVING: STRATEGIC, TACTICAL, AND OPERATIONAL DECISIONS OF THE DRIVER THAT IMPROVE VEHICLE FUEL ECONOMY

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User comments : 26

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ScottyB
3.8 / 5 (10) Sep 08, 2011
no shit!!
rgs
4.4 / 5 (7) Sep 08, 2011
I'm not usually a critic of articles posted on PhysOrg but I do come here in order to read material slightly above the "DUH" factor that this piece reflects.
Jaeherys
1 / 5 (1) Sep 08, 2011
You know, in science, "DUH" is not enough. It's obvious that you'll save money by driving slower and trying to keep your velocity the same as much as possible. But how much do you save? Is technique A or B more effective? To what extent can I go out of my way (ie. how far of a detour) to save fuel? These kinds of questions cannot be answered accurately without doing research.

On a side note, my Dad's not going to be able to weasle out of this argument now!
CreepyD
5 / 5 (3) Sep 08, 2011
Turning air conn off only benefits if you are driving slowly, less than about 40mph. Over that and you're better off having air conn on than opening the windows..
Also you would probably only need a 1 minute burst of air conn to cool you as much as 10 minutes with the window open would.
Doug_Huffman
2.3 / 5 (3) Sep 08, 2011
Will no one here ask what intensity, here - "Driving a light-duty vehicle ... is currently more energy-intensive than using a bus or a train and even flying," - means? Typically intensity is the rate of a dimension-squared. I submit Sivak's "intensity" is per passenger and comparing distance per passenger-mile for these vehicles. First we must kill all the Harley Davidsons.
antialias_physorg
3.7 / 5 (3) Sep 08, 2011
Turning air conn off only benefits if you are driving slowly, less than about 40mph. Over that and you're better off having air conn on than opening the windows..

But do you really open a window beyond 40mph (I mean _open_ it. Not just a crack).

CHollman82
4.3 / 5 (6) Sep 08, 2011
One thing I've noticed that saves me a lot on gas is to keep a good distance behind the person in front of me. Doing so provides a buffer for braking, you'll find yourself braking a lot less often and when you do it will often require you to slow down less than you would have if you were right on top of someone. I don't know how many physorg readers are American but it's amazing in America how many people like to ride 2 feet behind you at highway speeds, which is not only dangerous but awful for fuel efficiency.
Eikka
3 / 5 (2) Sep 08, 2011
Turning air conn off only benefits if you are driving slowly, less than about 40mph. Over that and you're better off having air conn on than opening the windows..

But do you really open a window beyond 40mph (I mean _open_ it. Not just a crack).



No, because that's a sure way to get hearing damage and a stuck neck.
Forestgnome
2 / 5 (8) Sep 08, 2011
This is a great example of people reading a supposed "science" article and accepting it as fact. This folks, is bad science. Anyone bother to read the study? All the data came from two sources, the EPA and an Edmunds magazine article. Most came from the magazine article, which by the way was nearly void of any data. I can tell you from being a mechanic and a gearhead all my life that this numbers quoted here are bogus, and my observations are easily as valid as this "study".
CSharpner
1 / 5 (3) Sep 08, 2011
"Eco" driving? You're never going to win converts with terminology like that. It just sounds so tree-huggy-ish, which just makes people sick these days. In spite of that, I practice these things myself to save on fuel costs, but every time I consciously do it, I recall the Governator making that ridiculous speech a year or two ago about "eco driving".

In spite of the fact that I've been practicing this, honestly, I'm not seeing a difference, and my car computer, which shows my mpg over long periods of time has dropped from 22mpg about 2 years ago to about 20mpg today. I even pumped in that expensive stuff while fueling that's supposed to clean out my fuel system to improve efficiency.

What's helped more than anything is taking Kroger up on their fuel points program. I'm now saving about $23 per fill up by working that system properly. It's not saving any fuel, but it sure as heck is helping my wallet.
CSharpner
1.3 / 5 (4) Sep 08, 2011
Frank, I know it's not what people want to hear, but the fact remains that that term really does irritate a LOT of people. If we want to encourage people to reduce fuel, we need to not use terms that are so clearly one-sided sounding.
CHollman82
3.8 / 5 (5) Sep 08, 2011
You realize "eco" could just as easily mean "economical" as it could "ecological"... right?

As in "economical driving"...
that_guy
not rated yet Sep 08, 2011
I think the article provides a service in talking about maintenance and driving styles, but it does a HUGE disservice by lumping in averages for vehicle types.

Number 1 should be about buying an appropriate and well designed vehicle for your need. For example, I need a truck. That doesn't mean i'm stuck with 17.2 MPG. My Ranger gets 24/29 - significantly above that average. If you need transportation for two-four people, get a small car like and elantra or civic. Low maintenance and high gas mileage in the high 30s...over 50% higher than the "car" average.

When you compare averages that include low volume/impractical vehicles (For most people) to include sports cars, f350s, etc - you miss the point that there is quite a range available.
emsquared
5 / 5 (1) Sep 08, 2011
People are coming on here saying "Duh", but how many people drive this way? 1 in 10? Less?

So it is either not obvious to the majority of people OR they can't manage their time OR they flat don't care. Except for those who don't care, a publication like this can only educate people or raise cultural awareness of it's legitimate importance and create interest in time-management. Either way, hopefully, the number of people who drive (what I would call) "sensibly" will increase. Who knows, we may even get safer roads out/lower health care costs out of the deal. This is a very direct, easy way in which a change in our culture would benefit "the common good" and environmental health. People who DO care should try to convince their friends to care, that's how change happens. Crazy talk, I know.
CSharpner
2 / 5 (1) Sep 08, 2011
You realize "eco" could just as easily mean "economical" as it could "ecological"... right?

As in "economical driving"...

Yes, of course I do. I'm not talking about ME. I'm talking about how many people view it. And I think most people realize than when most people use the term, they mean ecological, not economical, as in the context of this very article.

Do we disagree that many people view it as "ecological" and are turned off by it? Or are you (general "you", not "you" in particular) under the misinterpretation of my statements, thinking I'm proposing an anti-ecological stance?
emsquared
not rated yet Sep 08, 2011
I don't know how many physorg readers are American but it's amazing in America how many people like to ride 2 feet behind you at highway speeds, which is not only dangerous but awful for fuel efficiency.

It's not just America... ever been to Mexico City or Alexandria or Athens (and from what I've seen on the TV of any place like Singapore or Beijing or Tokyo)? Way worse, man. Monuments of driving inefficiency.
ROBTHEGOB
1 / 5 (1) Sep 08, 2011
DUH, DUH, DUH, DUH, DUH!!!!!! This is news?
glive
5 / 5 (2) Sep 09, 2011
Following too closely - dangerous certainly, but very fuel efficient. Another one of those adult trade-offs that we all must make. Article too dumb for further comment.
saberjim
3.7 / 5 (3) Sep 10, 2011
Most people that drive large personal vehicles don't have the personalities or brains to drive them efficiently or they wouldn't have bought them in the first place.
unknownorgin
1 / 5 (1) Sep 11, 2011
One of the big mileage killers that these studies fail to address is the effect on fleet feul economy and air pollution of starting and stopping tons of vehicles on highways because putting a stoplight up is cheaper than installing proper on ramps. Stoplights also cost motorist more at the gas pump.
tscati
not rated yet Sep 11, 2011
Cars average 23.7 mpg???? Do they make special cars for the US market with massive leaks in the fuel tanks? I know fuel prices in the US is ridiculously cheap, but those numbers are appalling.

Now, having adjusted the numbers for the weird so-called 'gallons' that they use in the US, even my 22-year-old Porsche 944 does better than 23.7 mpg! My knackered 12-year-old Fiat Punto still does about 45 mpg. And I've just ordered a new Skoda, 5-door hatchback, 105bhp, 0-60 in 10.9s. which should average about 55mpg (US gals) and I'm hoping will do about 65-70mpg on long runs. OK, it's a diesel, but the equivalent petrol model does about 47-48mpg.

It looks like the easiest way for Americans to halve their fuel consumption is to buy a sensible European or Asian car!
Newbeak
5 / 5 (1) Sep 11, 2011
Following too closely - dangerous certainly, but very fuel efficient. Another one of those adult trade-offs that we all must make. Article too dumb for further comment.

When we have road trains,cars can move at highway speeds inches from the car in front,and save gas.See: http://www.physor...deo.html
jsa09
5 / 5 (1) Sep 12, 2011
Driving a gas-guzzler? You can still cut fuel costs by nearly half


I do not think I can change any of my driving habits and improve mileage by anything more than 1-2% so where does the 100% improvement come in?

I suspect this should say that "If you drive like a maniac now, you can change your ways and cut fuel costs."
Magnette
3 / 5 (2) Sep 12, 2011
Most people that drive large personal vehicles don't have the personalities or brains to drive them efficiently or they wouldn't have bought them in the first place.


You win the prize for the most ridiculous comment on this thread!
People drive large vehicles for a reason. I drive a Discovery which I need for it's 7 seat capabilities and the fact that I can tow my race car with it. Not many family cars can pull a 2.5 tonne trailer safely so a large car is needed for it to be safe.

My Discovery is a diesel and will exceed 30mpg quite happily whereas my race car (which is road legal in the UK) will only do 4mpg driven carefully and on wide open throttle only does 0.5mpg...although you could never use w.o.t on a public road!

My race car is a lot smaller than the Discovery and a third of the weight which just goes to prove that size isn't always the issue. Engine efficiency/fuel type/ weight etc are all contributing factors.
CSharpner
5 / 5 (1) Sep 12, 2011
Cars average 23.7 mpg???? Do they make special cars for the US market with massive leaks in the fuel tanks? I know fuel prices in the US is ridiculously cheap, but those numbers are appalling.

They DO suck (literally and figuratively) on mileage. My Chevy Venture mini-van gets 20mpg. My wife's Honda CR-V gets roughly 22mpg. My van /used to/ get 22mpg when I first got it, but it's been slowly getting less efficient.

I suspect the difference is likely the average size difference between American cars vs. European cars. American streets are very wide and Americans tote lots of kids around with lots of sports equipment frequently, so they (we) tend to buy larger vehicles. Most Americans with kids are more safety conscious than fuel conscious, so they (we) buy what seems to be safer over what's more fuel efficient. They tend to ask themselves, "If my kid(s) were in a head-on collision, which vehicle would I prefer they be in? A big SUV or a little VW?" East answer.
that_guy
5 / 5 (1) Sep 12, 2011
Cars average 23.7 mpg???? Do they make special cars for the US market with massive leaks in the fuel tanks? I know fuel prices in the US is ridiculously cheap, but those numbers are appalling.

This is fleet average for all models in a segment. For example a chrysler 300 weighted the same as a mini. The actual US 'fleet' includes more small cars than big cars, but yes, due to SUVs and large innefficient cars, which just aren't popular in europe due to gas prices, europe has a better average.

Now, having adjusted the numbers for the weird so-called 'gallons' ....My knackered 12-year-old Fiat Punto still does about 45 mpg.

By US testing methods it would be 35-40. The new US mileage rating is more conservative than europe.

It looks like the easiest way for Americans to halve their fuel consumption is to buy a sensible European or Asian car!

We have small american cars that are equivilent or better. It is the large cars in the market that skews it.

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