Thoughts on Fuel Economy: How to Stretch a Gallon of Gasoline

Toyota’s engineers go out of their way to make our cars and trucks as fuel-efficient as we can possibly make them. But the one thing over which we have no control is how efficiently our vehicles are driven. This is critical, because the way you drive can have a huge impact on the fuel economy your vehicle obtains. Just ask any hypermiler.

You may have heard the term hypermile. It’s used to define a driving strategy for getting the greatest distance out of every gallon of fuel in a vehicle’s fuel tank - and maybe even exceed the vehicle’s EPA fuel-economy estimates.

Hypermilers have been known to take drastic measures to stretch the fuel economy of their vehicles. For starters, they lighten their vehicles as much as possible, tossing out tools, spare tires, even passenger seats. They might inflate tires to pressures considerably beyond the manufacturer’s recommended limits. They’ll drive with their vehicle’s windows closed to optimize aerodynamic efficiency, and they’ll turn the air conditioning off. They’ll shut their vehicles’ engines off when stopped in traffic, rather than let them idle. And they’ll keep speeds down – way down.

Speed, in fact, is a good place in which to start your search for better economy. Aerodynamic drag, a by-product of speed, costs fuel to overcome. The amount of drag your vehicle generates is not linear – it does not increase at the same rate as your vehicle’s speed does. Instead, drag is more or less proportional to the square of speed. It increases exponentially. So when you drive a little faster, you burn considerably more fuel.

The first rule of the day, then, if you’d like to spend a little less on gasoline, is to slow down. Whatever your favorite cruising speed is, back it down a bit.

Second rule of the day: Once you’re out on the highway at cruising speed and traffic permits, use your vehicle’s cruise control. You’ll burn less fuel if you do.

Third rule of the day: Check the inflation of your vehicle’s tires. Now, this one’s a little tricky. Under-inflation can greatly increase a tire’s rolling resistance, and that will cost you gas. Over-inflation generally tends to reduce a tire’s rolling resistance, but it also tends to concentrate the load on the tire on its center, which can lead to premature wear. Your best shot is to increase inflation to the maximum recommended by your vehicle’s manufacturer, then adjust pressures as needed to obtain even wear across the width of the tire. If you save gas at the expense of tire wear, what have you really gained?

Fourth rule of the day: Slow down for hills. Maintaining your speed up a hill means opening your vehicle’s throttle. A larger throttle opening means burning more gas. So you might want to think about backing down by a few miles per hour – maybe even five or 10 – for climbs.

Don’t increase your speed until you get to the very top of any hill you climb this way. In fact, if there’s a downgrade at the top of the hill, use that downgrade to help you increase your speed – let gravity help you to better fuel economy.

Fifth rule of the day: Connect your vehicle’s gas pedal to your brain. Every time you accelerate, think, “Hm, that just cost me some gas.” Do that, and you’ll soon rethink this business of acceleration. You’ll start accelerating only when you have to, and only as much as you need to.

Sixth rule of the day: When it’s time to slow down or stop, get off of the gas as soon as you can. If you have to climb onto the brakes, that could mean that you’ve stayed on the gas longer than you needed to. Use your brakes when you need to, but allow aerodynamic drag, rolling resistance and all the other forces working on your vehicle help you slow down.

While you’re trying these steps, do keep your vehicle’s windows rolled up – lowering the windows greatly increases the aerodynamic turbulence around your car, and thus increases the drag. To stay comfortable, use your vehicle’s air conditioning. It’s the lesser of the two evils. And resist the urge to tow or to use a roof rack or a rooftop container for extra gear. These have extremely negative effects on your vehicle’s fuel efficiency.

And there you have the basics. If you choose to give hypermiling a try, even if you don’t go to the extreme measures some hypermilers use, keep close track of your vehicle’s fuel economy. No matter what it is, Tundra or Corolla or anything else, you’ll almost certainly find that as you become adept at these strategies, you’ll begin to extract your vehicle’s full fuel-economy potential.

~ Contributed by Jon F. Thompson, Corporate Communications

Comments

[Nick]

What about coasting? I have employed this technique for a while now and find that it can easily give me a few more MPG. Every time I come to a downgrade I knock the car out of gear and coast down the hill (as long as I'm not going to hold up any traffic there is by slowing down too much). I also coast when approaching lights and any other situation where I know I will have to stop.

Another thing I've started doing is switching the engine off when I'm sitting at the lights or any other situation where I know I'll be stationary for more than 30 seconds or so. Why use valuable fuel just sitting there?

[robin]

I'm pretty sure Toyota is NOT making cars as fuel efficient "as we can possibly make them."

If that were true Toyota would be producing plug-in hybrids which get 100+ mpg.

But you don't do that. Why? I have no idea.

[steve landau]

Your rule 2 and rule 4 contradict each other. Why cant Toyota use the slope of the road from GPS to tell the cruise control this is a hill, and to keep power output lower.

I found with Cruise control on my Highlander Hybrid, I use more gas than carefully keeping the KW output under control by going down hills fast, and up hills slower.

[Stuart Kidder]

In the 70's, we were taught to drive like there's a tomato under your gas pedal, and an egg on your hood. Reducing "jackrabbit" starts, and slowly coming to a stop.
Also, what ever happened to the old fashioned vaccum gauge? This allowed the driver to monitor manifold pressure (vacuum) which has a direct correletion to performance and economy.

[donee]

Hi Robin,

Using the GPS would not work easily, as its not in every car. One thing they could do is allow the driver to set the control parameters (PID values in technical terms) of the cruise control. Specifically, the D , or differential value could be allowed to be decreased so that the control is not as snappy, and the engine RPM peaks are reduced.

Or, maybe a more acceptable method, would be a cruise control settings. For example - flat land economy, high accuracy, hilly terrain economy would be some of the settings. These settings would each have a different set of PID values and other things (such as keeping engine speed down - which max's economy, but slows load response) to accomdate the goal of the setting.

[Shane Tiernan]

Toyota: Any other ideas on how to commit insurance fraud? What a responsible corporation you are! Next you can build vehicles exclusively manufactured to smuggle narcotics equipped with hidden compartments and all! Pathetic! I will be encouraging my state legislators to STOP buying Toyota vehicles for their fleet. You should fire your ad company and issue an apology.

[Eloy Perez]

Congratulations!!!! this are very good tips. And as I know, Toyota is one of the company that builds the more efficient cars in the world...Also drive Stick instead of Automatic... it really reduces the MPG consumption.

[Tiredtubes]

It does work ...on a recent trip for a funeral in Bogalusa, La we traversed Louisiana (we're Texans)
achieved peak of 30.7 mpg in a 2wd 2007 v6 4runner...30 mpg on arrival
Just driving steadily, mostly not using the cruise and paying attention to whats ahead.
Nothing unusual...we do run 5-w40
synthetic Rotella and about 3psi extra in the tires (bridgestones)
Due to the ungodly traffic density on I-10 drafting trucks is
almost inevetable...(about 3 seconds back).
The 4 runner is about the best all around vehicle I've encountered...it's on par with my beloved '85 mercedes 300 tubodiesel..

[roy]

disagree with the windows. If driving slow it does not matter that much. Tune up the car, drive like you have a egg between your foot and the pedal, and in some cases loose some weight.

[Joe]

I have found that I can increase my MPG by up to 5 MPG just by coasting up to my stops as much as I can without upsetting the person behind me. I drive a munual transmission so it's very easy for me to do. Also I shift earlier than I used to trying not to exceed 3,000 RPM before I shift to the next gear, better yet 2,500 RPM.

[EDV]

Isn't frequently shutting down and restarting your engine harmful? I mean, would the starter motor heatup and decrease the life of the motor?

[Timothy Croom]

I am curious about why Toyota changed the gear ratio of the Corolla. I bought a 2001 Corolla S and a 2005 Corolla S with automatic transmissions. The 2005 engine runs about 200 RPM higher than the older 2001. As one would expect the older 2001 has always had the best mileage between the two vehicles. The 2001 now has about 200,000 miles and still outperforms the 2005 model on mileage. The 2001 typically gets 38-39 mpg highway and the 2005 gets about 35 mpg or lower. I still own both vehicles. The gear ratio reduction wasn't needed for power as both vehicles have ample power for driving both in the city and on the highway.

I have found on both vehicles that dropping the transmission out of overdrive when climbing hills that require a transmission shift to climb saves on gas. It would be a nice option to have a vacuum gauge on the dash to go along with the tachometer. This would be a convenient method of monitoring when to drop out of overdrive.

Is there a way to change the gear ratio of the transmission?