Hypermiling: The Complete Guide to Saving Gas

September 10, 2017

The average American spends more than $2,000 on gasoline each year. Obviously, most people would rather have $2,000 in the bank, where it could be spent on activities that generate far more utility than sitting in traffic and commuting.

As fate would have it, there is a growing population of “hypermilers” who share ideas that encourage efficient driving habits. Through hypermiling, you can change your driving habits and realize huge gasoline savings each year.

I’ve been hypermiling for about 10 years now. Like most worthwhile habits, this one requires careful thought and reflection. The reward for the extra effort behind the wheel is a huge increase in fuel efficiency. I’m talking 25%+ better than the EPA estimate, and 50%+ better than most other drivers on the road.

For example, we drive a 2015 Mitsubishi Mirage (3-cylinder). We routinely beat the EPA estimated 37 city / 44 highway, averaging about 45 MPG in mixed driving.

If you’d like to see similar numbers, here is how to do so.

Plan trips and avoid idle time

When the engine is cold, most automobiles burn roughly twice as much fuel. For this reason, it is extremely inefficient to take short trips in cold weather, and you should always group errands together in one major outing. When running errands, go to your farthest destination first, and hit the others on the way back. This ensures that your vehicle is as warm as possible during multiple starts and stops.

For the same reason, you should avoid letting your car “warm up” during cold weather. Instead of letting the car idle for several minutes, you can improve your gas mileage by driving under minimal throttle to warm up the engine.

Outside of weather considerations, there are navigation issues to think about. Before ever driving, you should actually think about the route that you will be driving. You can take note while you drive, or go online and map it out. Check for stop signs, stop lights, high traffic roads, etc. Always plan the path of least resistance. Sometimes, highways or rural routes offer an advantage in transit time and gas mileage at the expense of a few extra miles on the odometer.

Perhaps most importantly, avoid unnecessary trips during peak traffic. The herd of crazed and overworked commuters are most difficult to deal with in large numbers, so it’s best to leave them alone during peak migration (rush hour). They won’t like anything about hypermiling, and will try everything to disrupt your astute, cash-saving driving habits. Running errands at off-peak times can improve gas mileage, decrease time wasted, and greatly improve overall mood.

Fix bad driving habits

Once you hop in your vehicle and start driving, you must pay careful attention to your driving habits. When accelerating from a stop, you are getting terrible gas mileage (often 10 MPG or less). When coasting without your foot on the gas, you get incredible gas mileage. Obviously, the goal here is to minimize stop-and-go driving as much as possible.

Every time you press your brakes, you are killing the momentum that you just created by accelerating. When at all possible, don’t use the breaks. Pay attention to everything around you. Have your head on a swivel and always look ahead. Try to anticipate your next move, and try to time the next three stoplights.

Don’t run up on other drivers, and then throw on your brakes, and then change lanes and accelerate again. Think ahead, look around, and switch lanes when you must. Pay attention to the color of stop-lights. I see people accelerating to stoplights that are clearly turning red. Why would you do that? It’s going to be red, and you’ll have to stop. Instead, just take your foot off the gas pedal and try to avoid stopping at the light altogether.

In summary, stop accelerating and braking all the time. Try not to use your brakes at all.

**Note that in some situations, braking can help you maintain momentum.

For example: You’re doing well, coasting (not accelerating) up to that red light. If you slowly brake the whole time, you’ll quickly close the remaining road distance and be forced to a complete stop before the light changes to green. Or, you could press down on the brakes hard and early. When you brake hard initially, you can coast the remaining distance to the intersection at a slower speed. With sound judgment and a little luck, you’ll arrive at a fresh green light and avoid a full stop, which will boost gas mileage considerably.

Pulse and Glide

When you have to speed up, the best way to accelerate is under high throttle at low RPMs. In other words, press the gas relatively hard (maybe 60%, not 100% throttle) in the highest gear possible (lowest RPMs possible). This trick highlights one of the reasons that manual transmissions are vastly superior to automatics for hypermiling purposes – because you are always in control of the gearing.

Advanced hypermilers use this technique in something called the pulse and glide to set world records for driving efficiency. They shift into the highest gear possible, then swiftly accelerate to a modest speed. They then put the car in neutral (or turn it off) and coast back to the original speed. Then repeat.

It all might seem a little crazy and counter-intuitive, but it works because combustion engines are more efficient when working hard during short bursts than they are at working moderately hard in perpetuity. Take advantage of this by driving in the highest gear possible, which will keep RPMs low and gas mileage high.

This is all much harder to do in an automatic, and my best advice is to keep RPMs as low as possible while driving. This can be exploited after you start understanding your car and the natural shift points. In our old Saturn, which had a 4-speed automatic, I could increase throttle load and still keep it in a high gear at two distinct times. The first following third gear at roughly 31MPH, and the second after shifting into fourth gear at roughly 44MPH. Right after the car shifts, throttle can be increased without the car downshifting, which is an effective way to accelerate.

Coasting in neutral versus coasting in gear (and turning off the car)

When doing the pulse and glide, or just coasting down a big hill, there is often a debate about whether to roll in neutral or in gear. When you shift to neutral, your car is just idling, which uses minimal fuel.

However, most people don’t know that coasting in gear actually uses ZERO gas. Almost every car made since the 1990’s has a feature that shuts off the fuel supply when your foot is off the gas. This does come at a cost, which is the engine braking that accompanies being in gear. The car will automatically slow itself while in gear, so you have to weigh both options.

If you want to coast for a long period of time, and won’t be needing to brake, neutral is the better option even with the additional fuel cost. But if you are driving down a steep hill and don’t want a frictionless free-fall at full speed, leave it in gear to avoid using any gas, while enjoying a little bit of the engine braking that accompanies coasting in gear.

The other possibility when coasting is to simply turn off the engine when the car is in neutral. You should only do this if the coast will last longer than 12-15 seconds. If you need to use the gas before that, you are better off just idling. This is because restarting the car takes a small influx of gasoline, and causes minor stress on your car starter (which theoretically could die, but usually outlasts the car).

If you are going to be stopped for any amount of time, you should always shut off your engine. Don’t ever sit in parking lots with the car running. Don’t ever go through the drive through and sit idle for 5-10 minutes (just walk inside). You should probably even shut off your car on the way to a long red stoplight. After all, there is nothing better than tricking the people stopped next to you into thinking that you have a silent hybrid…

Highway driving and the A/C fiasco

Most engines are inefficient when running at 80MPH. Most cars reach peak fuel efficiency between 30-55MPH, and the sweet spot for many is right around 45MPH, right after they shift into the highest gear. If you keep top speeds between 75-80MPH on the highway, you’ll get 15-20% worse gas mileage than those who keep speeds of  60-65MPH. That’s neither good nor bad, it’s just more expensive. Is the extra speed worth the additional cost?

On long interstate trips, I’ll sometimes get behind a huge semi truck and draft. You need to maintain a few car lengths for this to be remotely safe, but you can see major improvement is gas mileage because of the reduced wind friction.

There is a bit of danger involved, but the reduction in drag, and therefore the increase in gas mileage, can be significant. A 2007 Myth Busters episode titled “Drafting for Money” produced the following findings:

Hypermiling drafting

In summary, drag is reduced 60% when following 10 feet behind a semi, and 21% even when seven car lengths behind. Fuel consumption is decreased nearly 40% at 10 feet, and still 11% even when trailing 100 feet behind. What distance do you feel justifies the increased risk?

Speaking of wind friction, did you know that it’s more expensive to leave the windows down then run the A/C on the highway? Somewhere between 40-50 MPH is the tipping point between the two. When driving under 40 MPH, having the windows down is cheaper. Above 50MPH, it’s cheaper to run the air.

If you’re considering running the A/C in city driving (low speed), you should know that doing so will often reduce gas mileage by 10%. There is a synergistic relationship between A/C usage and acceleration, meaning your gas mileage is absolutely terrible when doing both, and this will be most pronounced in cars like mine with very little horsepower to begin with. On cars with small engines, the A/C drag can be significant. To combat this problem, you can do a few things.  While decelerating, coasting or idling, turn the air on. While accelerating, turn the air off. Doing so will improve gas mileage.

Car modifications

A lighter vehicle is easier to move. Less weight requires less fuel to accelerate, and all else equal, a lighter vehicle will get better gas mileage. To begin, remove all accessory items from your car before driving.  Detach any outside accessories that add weight and reduce aerodynamics. Remove any dead weight and luggage that isn’t needed inside the car as well. For trips around town, think about ditching the spare tire and jack which weigh 50+ pounds.

In addition to reducing the weight, you can also reduce rolling resistance. Higher tire pressure means less contact with the road, and less rolling resistance while driving. In other words, highly inflated tires reduce friction between rubber and road, improving gas mileage. The only downside to fully inflated tires is a slightly rougher ride quality.

When inflating, don’t use the automobile manufacture recommendations, which are often around 30 PSI. Instead, inflate your tires to the tire’s maximum recommended PSI which is listed on the sidewall of the tire. I tend to inflate to the tire maximum without going over, but many people find that 1-3PSI of over-inflation will improve mileage further, without posing any safety issues.

How much will it improve mileage? Great question. Myth Busters found that over inflating the tires (60 psi vs. 35 psi, which was the manufacturer’s recommendation) reduced the fuel consumption of their regular sedan by about 7.6%. They also tested slightly over-inflated tires (40 psi) with the same car, which resulted in a 6.2% decrease in fuel consumption. 6.2% is a great improvement for basically no risk.

Rolling resistance and vehicle weight are the low hanging hypermiling fruit. You can do much more, but it requires more work and/or risk. Many people fill cracks and open spaces on/under the car to further increase the aerodynamics and decrease drag. You can also partially block the front intake opening on the car, which will make the engine run slightly hotter and actually improve efficiency.

Consider other transportation

If you embrace the ideas in this article, you’ll see a huge improvement in gas mileage. However, does it even matter if your car gets 10 MPG to begin with? I mean honestly, why do so many Americans feel the need to drive a huge, inefficient vehicle around town? It just doesn’t make sense.

Unless you have to haul 5 kids around town, or need a work truck, you really should be driving a compact car equipped with a 4-cylinder engine. That car should get at least 35 MPG on the highway. There are tons of used cars that fit my criteria, and most can be purchased for less than $8,000 in excellent condition.

In addition to finding a reasonable vehicle, how about just driving less altogether? I ride the bus everyday for free because my employer (local university) pays for unlimited use. The university actually includes unlimited bus usage in the tuition cost for students, but still it’s empty almost every day. Instead of riding the free bus, students pay for parking permits and choose to drive.

The best option is living close to work, and walking or riding a bicycle each day. Get your exercise while commuting for free. Now that’s a win, win.

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43 Comments on "Hypermiling: The Complete Guide to Saving Gas"

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Stefan
Stefan
First, great article! Two discussion points though: 1. From one of your responses to a comment: “Regarding turning off the motor, I wouldn’t call it dangerous in my experience. Most cars allow you to keep the power functions on if you keep the key in position for all accessories to remain on.” For most cars, the power steering and power brakes will _not_ stay on, since they are driven by a belt on the engine. If the engine is not turning, no PS and PB. However, (a) the vacuum reserve tank will give you about 3-4 applications of PB, and… Read more »
Joe
Joe
Overall, a very well-articulated article and I enjoyed reading that others find driving efficiently an art. I understand you are talking about increasing mileage by any means but I have some concerns about what you’re recommending to your readers. I’ve noted some areas of concern as follows: Drafting – Have I drafted a semi to see if it increases mileage? Yes I have and it works. However, I would never recommend it to others. It is disrespectful and dangerous to the other drivers and other vehicles on the road. Tire Pressure – Tires are part of the suspension system of… Read more »
Angela Waterford
Angela Waterford

The tip to plan trips is genius, especially because I haven’t ever thought about how much more energy and fuel my car needs if the engine is cold. I’m sure the wintertime only makes it worse because it’s literally cold! Thanks for bringing that idea to my attention. I’ll have to start really making plans for my driving instead of just running errands at random.

Clay
Clay
Why do people speed up to red lights? Because it’s fun to accelerate, that’s why! I pick my vehicles based on large size, biggest possible engine, and fastest 0-60 times. I’m currently driving an aluminum body v8 Supercharged SUV. I get about 14 MPG. However, I also only drive about 5000 miles a year, so I bet my gas usage is pretty similar to you guys in the 4 bangers. If you have fun hypermiling, great. But some of us have fun accelerating 🙂 I also slightly under inflate my tires to make the ride more comfortable and improve traction.… Read more »
Veronika Dalton
Veronika Dalton

These are really good tips. I wish I was better at the pulse and go. My husband’s car actually has a dual transmission so even though it’s primarily automatic, it has paddle shifters so you can go into manual shifting mode and quickly get into the higher gears.

Mark
Mark

Well, I can attest to getting over 45mpg in a midsize car that is rated at 35mpg highway. All I had to do was lay off the gas pedal. On the highway, I don’t go much above 60 staying in the right lane. In the city, I’ll drive about 5mph under the limit. I’m getting the same mileage as the hybrid trim for this car. Key – high gear, low rpm. Another benefit, I get to work calm and relaxed.

Nikki
Nikki

While I have never heard of the term hypermiling, after reading the article, I realie that I have already been applying some of the techniques. I have also learned a few more that I was not aware of. I appreciate this article especially since gas prices in my area jumped a whopping 10 cents per gallon in the last week alone. Thanks for sharing this valuable information.

Master Nerd
Master Nerd

Couldn’t of said it better myself! Although, I did say much of the same in my own post. Any idea what the impact of such high pressure tires is on tire wear? My understanding has always been that at very high pressures, the tire begins to deform and cause the middle of the tire to wear more quickly than the edges. It also reduces your contact area, which could be problematic on poor road conditions, but I suppose you can always adjust the pressure if needed.

BeSmartRich
BeSmartRich

With the gas price around $50 per barrel, I will just stick to pushing my accelerator to the floor on highways because I love the adrenaline pumping moment when driving. Just kidding:)

Excellent tips. I live with the smart habits all the time which have saved me at least 30% of my gas and maintenance bills.

Norm
Norm
I think I’ve been an amateur hypermiler without even realizing it. Your description of getting to red lights as they turn green is something I’ve been working on for years. I get the sense that it’s improved my mileage, but I really have no idea. But whenever I stop accelerating and coast ever slower towards the light, people hate it! Which makes me love doing it even more! There is a highway which turns into a boulevard near my house, with a stoplight soon after it switches. As I’m coasting down towards 35 or 40, people are still rocketing around… Read more »
Mitch Mitchell
Mitch Mitchell

Wow, this is some amazing stuff. I live in a cold area and I knew about the idling engine when one starts their car. However, it’s never occurred to me to go to the place that’s the furthest first. I’ve always gone in order and in a pattern that I thought shortened my distance, and that a warmer engine would be more efficient; great stuff!

I also put on significant highway miles but I don’t think my psyche could handle being behind a truck for any length of time if I could help it. lol

David
David

One part of hypermiling I recommend not doing is shutting the engine off when coasting.If you do this the power steering and power brakes will not function which can be unsafe if you need to make a sudden move. I know hypermiling is about avoiding sudden moves but you never know what someone else will do. With some cars the automatic transmission can be damaged by rolling with the engine not running. Transmision repairs are much more expensive than a gallon of gas.

Joseph Hogue
Joseph Hogue

Wish I saw this post when I had a car. One of the advantages living in a big city with a great transportation system. So glad you didn’t recommend riding up close enough behind someone on the freeway to draft them. So dangerous and doesn’t save that much.

Most people don’t consider the possibility of just driving less and walking or bicycling when they can. Depends on where you live but try doing your grocery shopping close enough to home that you can walk.

Keenyn
Keenyn

Here is the #1 way to save on gas, don’t drive!! I ride my bike as much as possible, especially because I live in a bit city and it’s amazing! Car doesn’t break down as often, I only buy gas about once a month or month and a half.

Cheap Mom
Cheap Mom

My gas use is something that we haven’t really started to focus on yet. I’ve heard of hypermiling and it’s funny how backwards some of the common sense ways to save fuel are (slow acceleration?). I like that you included the low hanging fruit for us though, I’ll be pumping up the tires next time I fill up!

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