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The News

Everyone wants to save gas (and money). We can’t control the price at the pump, but we can control our own driving. Reducing fuel consumption is easier on our wallets, our cars, and our environment. Thankfully, researchers have found that it’s not that hard to do exactly that.

A new study from Michael Sivak and Brandon Schoettle at the University of Michigan’s Transportation Research Institute has found that increasing your fuel economy can be achieved by practicing a few simple “eco-driving” techniques, being mindful of your car’s condition, and simply buying the right car.

The Study

It’s a pretty bleak outlook to begin with. Though cars in Europe have been getting up to 75 miles per gallon, the mean fuel economy for cars on American roads has never gone above 25. Here’s a look at our current state:

Our average fuel economy for cars in 2008 was 22.6 mpg, which isn’t that great. Most of us own cars that just can’t reach the mpg of a Prius or Polo, so what can we do?

Reducing Fuel Consumption

Strategic Decisions: Select The Right Vehicle Class

This is the factor that by far has the greatest effect on fuel efficiency. For example, on average, switching from a pickup truck to a car will result in a 38% improvement. If you want to save money and gas, the first place to start would be to buy a car type with a good fuel economy. Think Smart-Car over F-150.

Select the Right Vehicle Model

The type of vehicle is also important. Basically, cars beat vans which beat SUV’s which beat pickup trucks. Of course, within these models an electric or hybrid is the more fuel-conscious choice. The best fully electric car and the best car overall gets 99 mpg; the best hybrid car gets 50 mpg; the best car with internal-combustion engine gets 36 mpg (averages).

Select the Right Vehicle Configuration

There are currently 282 vehicle models for sale in the U.S. (model year 2011), with 242 models having two or more variants (e.g., engine size, number of doors, etc.). For 216 of the 242 models with two or more variants, the rated fuel economy differs among the models, depending on the variants, by up to 5%. When choosing the configuration of your car, make sure you’re looking for the one with more mpg.

Take Care of Your Vehicle

It seems obvious, but if you want your car to run well, you have to take care of it and do the necessary maintenance. Here are a few reminders that directly affect your mpg’s:

  • Keeping you engine tuned correctly= increase of 4%
  • Keeping your tires correctly inflated= an increase of 1-2%
  • Keeping your engine oil current = an increase of 1-2%

Saving gas now is as easy as giving your car a check-up every 3,000 to 5,000 miles.

Tactical Decisions: Drive on Consistent Roads

Quoting the study:

Different road types result in different average speeds and different profiles of acceleration and deceleration. Consequently, fuel economy differs by road type. For example, a recent Canadian study (National Resources Canada, 2009) found that the average fuel economy on highways with a posted speed of 80 km/h (50 mph) or more is about 9% better than on other roads.

In short, choosing consistent highways over changing roads will increase your fuel economy.

Drive on Flat Roads

This one is important. When selecting which road you should take to work, it is far more fuel-efficient to choose a road that is flat and has few hills. One study found that avoiding hilly roads in favor of flat ones can increase mpg by up to 20%.

Avoid Traffic and Congestion

It shouldn’t be a surprise that being stuck in traffic and constantly stopping and starting will take a toll on your gas gauge. The reason is that the more you stop and start, the more you have to re-overcome your car’s own inertia to get it rolling again. The amount of gas to keep the car rolling is less than the amount it takes to constantly get it rolling.

The Department of Transportation rates congestion from A to F, with A being free-flow and F being traffic resulting from a breakdown on the road. The fuel economy difference in choosing a route that has a congestion rated A versus one that is rated F is an increase of up to 40%.

Carry Less Weight

Be mindful of how much you are hauling around in your car. According to the EPA, every 100 pound increase in weight will result in a 2% reduction in fuel economy, with smaller cars being more affected. Carpooling will save gas collectively, but carrying around extra girth will cost you at the pump.

Operational Decisions: Don’t Idle Too Long

Idling can use up to half a gallon per hour, depending on the engine size and configuration. Studies show that it is recommended to turn off your car when expected idle times are more than a minute. Contrary to popular belief, starting your car costs only a few seconds of gas.

Waiting for a train to pass or your date to be ready? Turn off the car and save some gas.

Find the Best Speed/Rpm for Your Vehicle

Contact your dealer (or manufacturer website) to find out what the optimal speed/rpm is for your car regarding fuel consumption. In one study, the V6 engines used in Honda Accords were rated 30% more fuel-efficient at around 60 mph than they were at either 30 mph or 90 mph. It makes a big difference.

Use Your Cruise Control

It is estimated that using your cruise control at highway speeds can increase your fuel economy by 7%, so set it when you can.

Use Air Conditioning Sparingly

The use of your air conditioning system can reduce mileage by 5%-25%, however, opening your windows above a certain speed will increase aerodynamic drag enough to result in the same reduction.

As a general advisement, if you need to get cooled off, air conditioning at above 45 mph is preferred, with a preferred use of windows below that speed. However, if you can stick it out, using neither will save you gas.

Don’t Drive Fast and Furious

In one study, drivers who drove more moderately used 31% less gas than drivers who drove aggressively. This depends on the degree of aggressiveness, but the secret to better mileage is calmly managing your speed (don’t quickly accelerate from 60 to 90 mph just to pass someone on the highway) and accelerating more slowly from rest.


As the table outlines below, all of these decisions can greatly influence your fuel consumption, with the greatest factor being your initial vehicle selection.

Some of the percentages referenced in the above table may not seem like much, like only 1-2% for improper engine oil, but this small percentage, taken over tens or hundreds of thousands of miles, equals a lot of wasted gas.

So what is the practical effect for the driver today? The study also gives an example of what would happen to the fuel economy of a standard car if none of these decisions were taken into consideration.

Dropping from 36 mpg to under 20 could cost you hundreds or even thousands of dollars over the lifetime of your car.

There are relatively simple ways (barring the purchase of a new, more fuel-efficient car) that you can increase your time between pumps today. You can do it right now and see the effects for yourself. It helps your wallet and the planet. Win Win.

[But I’d start looking at electric cars if I was you.]