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Report suggests that not following good eco-driving practices can lead to a reduction in on-road fuel economy of up to about 45% in total

The types of vehicles consumers select has by far the most dominant impact on on-road fuel economy—the best vehicle currently available for sale in the US is nine times more fuel efficient than the worst vehicle. However, remaining factors over which a driver has control—route selection; vehicle load; vehicle maintenance; and the driver’s own behavior—can contribute in total to about a 45% reduction in the on-road fuel economy per driver (i.e., a fuel economy penalty), according to a new report by Michael Sivak and Brandon Schoettle at the University of Michigan Transportation Research Institute (UMTRI).

The report on Eco-driving also suggests that increased efforts be directed at increasing vehicle occupancy, which has dropped by 30% from 1960. That drop by itself, note Sivak and Schoettle, increased the energy intensity of driving per occupant by about 30%.

Average on-road fuel economy in the US for all vehicles in 2008 was 17.4 mpg US (13.5 L/100km); in 1923, the average was 14.0 mpg (16.8 L/100km). Driving a light-duty vehicle in the US currently is more energy intensive than flying, not to mention using a bus or a train (all at current average loads).

How can we improve on this performance? This report reviews how eco-driving enables drivers to maximize the on-road fuel economy of vehicles. In this report, eco-driving is used in its broadest sense: Eco-driving includes those strategic decisions (e.g., vehicle selection and maintenance), tactical decisions (e.g., route selection), and operational decisions (e.g., driver behavior) that improve vehicle fuel economy.

—Sivak and Schoettle

Factors related to vehicle maintenance that impact fuel economy include engine tuning, tire selection and maintenance, and weight of engine oil. Tactical decision for drivers include:

  • Selection of road type (including speed limit and patterns of acceleration and deceleration);
  • Selection of grade profile;
  • Dealing with congestion;
  • Weight (i.e., loading). (On a related note, the average adult in the US in 2002 was about 24 pounds heavier than in 1960, resulting in a reduction in fuel economy of up to about 0.5%.)

Operational decision (driver behavior) that affect fuel economy include:

  • Idling;
  • Speed/rpm;
  • Use of cruise control;
  • Use of air conditioner; and
  • Aggressivity of driving.
Summary of effects of factors influencing vehicle fuel economy
other than vehicle selection and configuration
Strategic Out-of-tune engine 4–40%
Tires with 25% higher rolling resistance 3–5%
Tires under inflated by 5 psi 1.5%
Improper engine oil 1–2%
Tactical Route selection: road type variable
Route selection: grade profile 15–20%
Route selection: congestion 2-–40%
Carrying extra 100 pounds ≤2%
Operational Idling variable
Driving at very high speeds 30%
Not using cruise control 7% (while at highway speeds)
Using air conditioner 5–25%
Aggressive driving 20–30%

As an example, Sivak and Schoettle calculated that a car that nominally gets 36 mpg will experience a reduction to 19.8 mpg in actual fuel economy (a reduction of 45%) as a result of disregarding all eco-driving practices.

The research was supported by Sustainable Worldwide Transportation. The current members of this research consortium are Aramco Services, Autoliv Electronics, Bosch, China FAW Group, FIA Foundation for the Automobile and Society, General Motors, Honda R&D Americas, Michelin Americas Research, Meritor WABCO, Nissan Technical Center North America, Renault, and Toyota Motor Engineering and Manufacturing North America.



Dave R

There's 2 major things that kill efficiency:

1. When on the highway, high speeds - the difference between 60 mph and 70 mph is typically about 20% less efficient.

2. Rapidly changing speeds - on surface roads this is a result of poorly timed lights - on the highway, it's typically a result of not looking far enough down the road to anticipate changes in speed.

On surface roads around here where speed limits are 35-55 mph, my average speed is typically below 30 mph because of lights. This hurts efficiency 20-30% compared to avoiding stops and being able to avoid braking.

Solution? Lower highway speed limits and either smart traffic lights and/or round abouts.


Typical hotatory and utopian "improvements" produced by hectoring everybody.

Intolerantt toatalitarians have been trying to "perfect Man" since time immemorial. It only leads to dystopias and consequent misery, concentration camps, and dictatorship.


Not for Texas. It would be against the State's interests.

Henry Gibson

People gave up the right to complain about energy efficient devices when they allowed efficient refrigerators to be required and the 100 watt incandescent bulb to be outlawed. Inefficient automobiles and their inefficient operation costs the US the extortionary demanded price of speculators in oil rather than free market prices. Automobile energy from electricity is about one fourth to one fifth the price of energy from gasoline. Energy from coal converted to liquids could be one third the cost or less than the cost of petroleum energy.

Hydraulic hybrids can reduce fuel use and cost to half.


HG....I agree with you that partially and fully electrified vehicles would be extremely beneficial for USA's economy and certainly for our well being. Unfortunately, oil lobbies, other liquid fuel speculators (ethanol, biofuels, CTL etc), most vehicle manufacturers, many million naysayers and elephant party political bickering will do their best to delay or block their mass production.

Coal to liquid fuel may not be much better than current crude oil but it could reduce crude oil imports. Of course, coal people will support it.


@ "D"
We can't change the nature of man, but we can reward socially desireable behavior and disincentivize deleterious behavior. We've been doing it since we mandated driving on the right side of the highway (or a consistent side0 and outlawed murder. Trickier behaviors are those with less binary definitions. For those we need gradations of reward and disincentive.

A few weeks ago we talked about using the ecodriving coach capabilities of Honda Insights and other vehicles, combined with a black box that logs data for occasional rewards or fines, perhaps during smog checks. Any system can be gamed positively or negatively, but if we set up meaningful incentives, rational individuals will on average do rational things.


I would be happy to let "D" and his fellow knee-jerk reactionaries drive like 1di0ts, on one condition: that fuel was taxed as if every penny spent at the pump gave aid and comfort to the enemy... which it does.

It doesn't matter how people move away from petroleum. The radical's idea of walkable and bikeable communities works. The Chevy Volt works. Eco-driving works. Ford's half-sized techno-tweaked engine works. Electric cars work. We need a system which rewards people for picking one.


EP, most of the items you mention do have economic rewards already. Granted the EVs are too expensive. But we have proved they work. And as cost decreases and people realize the 35 EV miles costs them less than a dollar (140MPGe) - they'll think hard on buying one.

The best incentive for many "behavior mods" is economic. If people save money they can use for other items: education, entertainment, homes and improvements - they will practice some of the items you mention. D, is a reactant to the idea he must do this stuff at someone else' demand - with no reward except loss of choice. Imagine how that would pis*off pregnant women.


Thus my proposal for a deductible on Social Security payments, financed by taxes on motor fuel. It incentivizes work and frugality, and the citizen gets to keep anything they can get through the savings.


One problem with using the economic incentive for "behavior mods" is that the extra costs are usually upfront and the payback is spread out over a long period of time. Too many people are "penny wise but pound foolish."


The outdated idea that Americans will only buy what they want doesn't hold up to new realities. Currently, and in the near future, we (50+++%) will progressively be compelled to buy what we can afford. That has started and is the main reason why Walmart (and similar low cost goods stores) have been doing so well while seaside $1M condos are unsold. That trend started almost 10 years ago in Japan facing a long lasting economically troubled period.

Those of us who still believe that we will soon be able to afford Hummer style gas guzzlers will face a rude awakening in a few short years. The monster vehicles days are behind most of us.

In the not too distant future, most of us will drive ultra light mini e-cars or use public transports or both. Changing leaders will not be the miracle solution that the majority is inclined to believe.


ai_vin: that's what feebates are for.


I know, but how do you get THAT passed into law?

Henry Gibson

Every automobile made today can be limited in speed and acceleration by the built in computers. It is also now cheap enough to have the automobile computers record and report every road and speed traveled on that road and when, and it could be made mandatory that the data would be downloaded by the pump when buying gasoline. ..HG..

Henry Gibson

It is now possible and economical to record all paths a car takes and at what speeds. The car can be controlled for both speed and acceleration. The driving events can be downloaded when the fuel tank is refilled, and uneconomical or even illegal driving can be noted. ..HG..


Thanks, Henry. You just set back the idea ten years by effectively equating it with the imposition of a surveillance/police state.


Here's more detail and more enlightened approach to this make-us-all-hypermilers program, based on a recent grant to UC Riverside.


This amuses me because in the UK, local transport officers are justifying their own jobs by bidding for "sustainable transport projects" involving:- narrowing roads badly with random pinchpoints; painting acres of centre hatching; forests of traffic lights and signs; and putting in the odd token cycle lane here and there which stop and start where the other random pinchpoints have been created (thus creating conflict spots between cyclists and vehicles).

Is this sustainable transport? No, its simply engineering in congestion which paradoxically increases fuel consumption through more stopping and starting and queuing?

Worse still most of these measures are turning streets into the urban equivalent of a "Total Wipeout" course. They are poorly designed, disrespect street character, usually with uneven gobs of tar filled islands and paint laid by people who have no concept of the words "neat", "symmetry", "quality" or "pride". In turn, these traffic engineered (read vandalised) environments make places feel more unsafe than they were to start with.

Approches like this stink of doing something for the sake of it, instead of making true efforts to provide more walkable streets and smoothing the flow of traffic and both aren't necessarily incompatible if schemes can be planned and implemented properly.

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