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Increase your gas mileage: A guide to 'hypermiling'

On today's show, I gave Kai a lesson on hypermiling, a method of driving that can increase your car's gas mileage and in turn save you from spending so much at the pump.

Want to give hypermiling a try? Here are a few of my tips:

Things you can do before you even get into your car...

• Make sure that your tires are properly inflated. Under-inflated tires are also a sure-fire way to rob you of fuel economy because of increased rolling resistance.

• Plan your trips accordingly. Your car starts and runs more efficiently when it's been driving for a while. So if you have to take a trip to two places, go to the one that's further away first.

• Remove excess weight from your car. If you have things like golf clubs, suitcases or anything else that you don't need on a daily basis, take them out. More weight = more for the engine to move.

• Basic maintenance. Take your car in for regular check-ups. Clean oil and clean air filter mean better MPGs.

While you are driving...

• Slow down! Driving 80 m.p.h. on the highway as opposed to 60 m.p.h. on a short trip won't get you there much faster. But depending on your car, it could cost you $2.

• Look down the road and pay attention! If you can anticipate what lies ahead, you are already operating the car more efficiently.

Some basic techniques:

• Timing lights. Try to figure out how the lights work on some of your drives. Like if a light turns green, maybe the next few will turn red right after -- then you know you can go much slower since you'll catch a red light anyway.

• Coming to a red-light or stop sign. Don't wait 'til the last second to brake. If you see a red light coming up, let off the gas and slowly brake to your stop.

• Minimize the time spent idling. If you need to stop for a while -- turn your car off. This means always skipping the drive-thrus!

• Driving without brakes (DWB). Try to drive with the minimal amount of braking. When you brake, you're just wasting the gas to get back to the speed that you were at.

• Driving with Load (DWL). An engine runs more efficiently in a narrower power band. So try to keep your car from deviating too far from a certain RPM.

• Anticipate Hills. Your engine has to work harder to take you up a hill. If you are approaching a hill -- accelerate to build up some speed.

• Minimize Cruise Control. If you're driving in a hilly area, it's best to turn your cruise control off.

• Slow Acceleration. Quick acceleration robs you of you MPGs. Accelerate gently and smoothly.

• Turn off the A/C. Your air conditioner can decrease your MPG by up to 30%.

• Accelerating from a stop technique. Your engine has to work that much harder to get the car moving from a dead stop. So when the light turns green, take your foot off the brake and let the car roll for a few seconds. Then apply the gas and start accelerating forward.

Rance Russo is a hypermiler and a commercially licensed pilot. His website is Every One MPG.

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I'm surprised that Rance didn't recommend watching the instantaneous fuel efficiency gauge (miles per gallon or kilometer per liter). Years before I'd ever heard of "hypermiling", that's what I experimented with. A goal I've tried to follow is to choose a minimum MPG (15, say) and try to stay above it, almost all the time.

I was also surprised that Rance gave so few statistics on how much of a difference these techniques can make. I've found that I can improve my efficiency by 20%, on some trips, just by altering how I press the gas pedal.

Another example where short-sighted, tailgate-style driving, as opposed to anticipate-and-decelerate-slowly-style driving, is less efficient for the entire population is in stop-and-go traffic. If everyone would just cruise along in a smoother manner, there wouldn't be so many sudden-braking and sudden-accelerating shock waves in the traffic flow, and we'd collectively achieve a higher throughput.

Some day our semi-autonomous cars will help us do this.

When going down a reasonably long hill (1/4 to 1/2 mile), is it a gas-saver to switch gears to neutral? Also, I've been told that driving at highway speeds with windows open creates a lot of drag and uses more gas than driving with AC on. Is this true?

Don't make a habit of shifting into neutral- if you make a mistake and shift into reverse it will erase any gas savings for many many years!

Pretty much a wash with the a/c at highway speeds. Slower than that windows are a bit better. If it's too hot to drive without opening up or A/C, just be comfortable.

Neutral is usually more efficient than coasting in drive, but at higher speeds the boost of gravity on a downhill may not be quite enough to keep you at the speed limit. Also, sometimes when coasting to a stop light I count on that drag of the transmission to slow me down without braking (hybrid owners with regenerative brakes should just brake slowly as that recharges the batteries).

I want to address the issue of coasting to your stop. On most modern, fuel injected cars, and this goes for my 20 year old Honda, when you close the throttle, and the engine speed is over 1,300 rpm, the fuel injectors totally shut off. Obviously, this saves fuel. So, coasting in gear, would normally be preferable to coasting in neutral. Of course the grade of the road and the distance you have to travel can come into play. Normally, I keep the car in gear, and my foot off the clutch. I will also downshift to keep the "revs up" at an appropriate level".

Dear Kai,

I enjoyed your segment today on Hypermiling and have always considered myself a conservative driver who tries to get the most from a tank of gas by avoiding jack-rabbit starts and such.

But I have to take issue with Mr. Russo's tactic of coasting to a stop at red lights. The driver behind you who gave you a dirty look may have had good reason for doing so. He might have wanted to make a left-hand turn which requires him to get into the little piece of road real estate that, on smaller roads, typically extends only a dozen or so yards back from the intersection. Those lanes often use a tripping mechanism to tell the traffic light whether or not to even bother with the left green arrow. If no vehicle is present at some pre-determined time prior to the lights turning green for the other lanes moving straight, then there is no left green arrow for that cycle. By coasting your way to the traffic light, you may have robbed one or more motorists behind you of the opportunity to get into that left-turn lane and trip the mechanism that will allow them to safely make a left-hand turn during this cycle. Sure, you may have saved gas by coasting up to the signal, but that would have been offset by the extra gas used by the other cars idling for another minute or so in the left-turn lane waiting for another cycle of the traffic light. Even if it a wash in terms of overall gas savings, it is inconsiderate of other drivers.

That is a pet peeve of mine and ranks right up there with folks who don't appear to know what a turn signal is for.

Thanks for listening,

Rich Sartore
New Smyrna Beach, FL
386-576-6877

Proudly driving my 2005 Dodge Caravan more than 125 miles on my daily commute!

The point about preventing a following driver from reaching the left-turn pocket is true, and I get annoyed when it happens to me. But I really don't think it balances the basic principle of not racing up to the red light, which can help everyone save gas every time. Maybe we can estimate the extra time and gas used by the left-turner waiting an extra cycle on the signal: how many are there, how much gas, how much time? I doubt it's very important in the scheme of things.

If everyone went at a more constant speed, then that would be the norm, opportunities to turn left a few seconds sooner simply wouldn't exist, and overall gas usage would be less.

I need to point out that this method of driving (hypermiling) is generally as fast, and safer then the usual method of driving.

We've all seen them. The idiot who is furiously changing lanes every other car, tail gating the last of ten cars who are in the left lane, driving well over the speed limit, each tail gating the car in front, they practically stand on the brake at lights because they are not paying attention to whats going on in the distance, and they seem to sincerely believe that tailgating me, while I am driving behind another car in the right hand lane, will increase the speed of the other driver. They drive like this in the sun, rain, snow, and are responsible for many truly nasty accidents on the road.

Lets call them what they are. Selfish child like people who don't care about anyone else, or anyone's safety or well being, including their own or their families. Reminds me of the time I was tailgated (a foot from my bumper) by a fool with his wife and new baby in the car, along with the "baby on board" sign. His excuse... I didn't pull away fast enough. Because I checked first that no-one was going to run thier red light.

I'm a hypermiler because I want to save money on gas, on wear and tear on my vehicle, and I want to be around for my family. So I drive with safety in mind, which also corresponds with hypermiling.

Those who whine about me driving too slow (when I am actually driving a few mph above the limit) can consider themselves selfish child minded as well. They think they can beat time, but they can't, nor can they beat the laws of physics. The faster you drive, the less your reaction time, the longer your braking times the harder and more damage you do when you hit. If you think you can beat the laws of physics, your daft. Or you have a child mind.

And when you do get yourself into an accident, you will whine that it was an accident, even though you drive like a fool and there are almost no "accidental" vehicle collisions.

When a deer jumps in front of your car, its an accident. When your driving well over the speed limit while tail gating and you hit someone, its all on you.

FYI: a child mind is a mind that doesn't connect action with consequences, and tends to believe in wish fulfillment. Because they want something to be true, they believe it is, even in the face of evidence showing it isn't. There are many people who are affected by this sad condition. Most of them seem to drive.

I wouldn't really consider myself a hypermiler, but I do watch my milage closely.

Here's a way to save gas without annoying everyone else on the road. Only put in about a third of a tank at a time. The less fuel in the car, the lighter it is - which increases your gas mileage. I've been doing this for a couple years now and it does make a noticeable difference. Before when I would fill up my tank all the way I was getting around 32-33 miles per gallon. Now, I only put in about a third of a tank and drive til my gas light comes ne. Doing this gives me about 37 miles per gallon.

While a gallon of fuel does weigh roughly 8 pounds, filling up only a third or less of the way can actually decrease your mileage, depending on the frequency with which you operate your vehicle. This is because when you have a full tank of gas, while it weighs more, there is little air in your tank so less of your gas is lost to evaporation. The less gas you have in your tank then the more air you have, and the more gas you lose to evaporation.

If you operate your vehicle frequently and with considerable mileage every day, as most people with commutes do, it would make more sense to fill up to the 1/3rd level. If however, you are like me, and you infrequently use your vehicle and do not travel very far, it makes more sense to fill up every time you are at 1/2 to 2/3rds capacity so as to minimize the evaporation effect when your vehicle is not in use.

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