So many times, when it comes to achieving higher mileage, people focus on their car and how they drive. Most times, they just assume the commute is an unavoidable variable. A predefined route that some days has good traffic while other days has bad traffic. This article will explain why the route you take and how you drive it plays as much a role as all other variables. When it comes to improving, never consider anything to be predetermined. The goal is to scrutinize everything.
Find a Mileage Friendly Route
If you happen to live in a large city, there’s a very good chance there are multiple options when it comes to the daily commute. Personally, I have three choices that I will call “Fastest”, “Easiest”, and “Hypermiling”.
“Fastest”: I have the opportunity to hop on an interstate for about ¾ of my commute. Doing so would save about ten minutes and is an attractive option when time matters. The downside is that the interstate maintains a relatively constant 70 – 80 MPH except when it comes to a screeching halt for no particular reason before slamming back up to 70 MPH. In other words, exactly the opposite of hypermiling.
“Easiest”: There is a state highway that runs is literally a straight shot from town to town. Albeit, one with multiple stoplights. Like the interstate, traffic is either racing along (though closer to 50 MPH), stopping for the red light, or accelerating Grand Prix style at the green light. It’s a multi-lane stop-and-go early-morning ball of stress. In no way do I look forward to starting or ending my day on this drive.
“Hypermiling”: This drive is 5 miles and 9 minutes (on average) longer than the “Easiest” route. This drive has longer stretches without stoplights and some stoplights are timed. It passes two schools and one nature preserve. The highest speed limit sign is 45 MPH. It is on this route that I see joggers, walkers, and the occasional wildlife. On nice days, I drive this route with my windows down enjoying the sights and sounds. All the while, the speed is conducive to attentive hypermiling and plays into the capabilities of my car.
By selecting a different route, I can not only achieve better mileage, I can choose how my day starts and ends. If you find that you arrive at work already stressed and you return home mentally ragged, do yourself a favor and seek out a more casual and hypermile-friendly route.
Memorize Your Route
Here is an analogy parents can appreciate. Let’s say your son goes to the first day of school and is presented with a difficult, lengthy exam. How would you expect him to score on that exam? Probably not very good. On the second day, he is presented with the exact same exam. Should he do better than the day before? Perhaps. Let’s pretend your son is presented with the exact same exam every day for the entire 180-day school year. You would expect him to be acing that exam with absolutely no effort, wouldn’t you?
Now what about people working an average 250 days per year? Most of them drive the exact same route every day, to AND from work. Even after all this repetition, it has been my experience that people drive their daily commutes as though it’s their very first time. Every time.
You are a human (I hope). You are preprogrammed to identify and memorize patterns. It’s what we do.
If you drive a hybrid, consider basing battery usage on drive segments. Pick up some charge during the fast segments in order to run farther on battery during the slow segments. Or vice versa: consider going deep into the battery pack if you know an upcoming faster segment will allow you to recharge. Recharging will impact the instantaneous mileage. Ignore that; it’s the average that matters.
It’s all about driving the same route every day, figuring out what works best, and repeating it.
Document Document Document
“What is documented can be tracked. What is tracked can be improved.” Or something like that.
To be clear from the start, this isn’t about keeping a detailed diary or “Driving Journal” unless that’s your thing. Even just recording the tank-by-tank averages provides insight into the kind of mileage that can be expected at different times of the year or during different types of drives.
When I bought my 2004, I started tracking my tank-to-tank mileage. After a while, I started adding the average temperature experienced during that tank. It was an average of all the highs and all the lows. Not scientific but good enough. It wasn’t long before a pattern took shape showing a direct correlation between ambient temperature and average mileage. Until that time, this connection had been suspected but never clearly documented. It helped me set a baseline for what to expect and helped the community understand the connection.
What you document is entirely up to you. Perhaps you want to experiment with different routes to find out which returns the highest mileage. Some people would drive each route once and make their decision but this is a foolish and shortsighted approach. Single data points do not represent trends. On any given day, traffic might have been lighter or heavier than usual; the only way to know is to drive the route multiple times and document each pass. Make your decision based on the averages of each route, not a single day.
If you have the opportunity, drive a route that returns the highest mileage. If it turns out to also be least stressful, then it’s a double-win. The only way to know which route is the most fuel-efficient is to document each pass in order to develop an average and recognize patterns. Once the best route is identified, memorize how to handle each segment with the intent of getting better with each day.
Check Your Tires’ Pressure
According to FuelEconomy.gov, under-inflated tires can lower your mileage by 0.3% for every 1 psi drop of all four tires. Other sites put the figure at 0.4%. Even though it doesn’t sound like much, the point of this ongoing series of articles to make clear that all things – when taken together – can account for a significant improvement in overall efficiency.
When to take the Measurement
Hot air expands.
That’s it. Now you understand how the temperature of the tire will affect the temperature of the air and therefore the measurement of pressure. Always measure the tire pressure before driving the car. Taking the measurement after a long drive – especially at high speeds – will return a deceptively high reading.
Ideally, you should measure your tire pressure every month. First of the month? Check your pressure.
Winter versus Summer
In addition to hot air expanding, cold air constricts. Most sources put the anticipated psi drop at 1psi for every 10 degrees of temperature drop. In some locations, the difference between the hottest Summer day and the coldest Winter morning could be more than 100 degrees Fahrenheit. For tires, that’s a potential 10psi swing.
When Autumn comes, don’t be surprised if the tires start reading low. It will be necessary to add air to maintain pressure. In the Spring, – and this is important – it might be necessary to remove air to keep the tires from becoming inadvertently over-inflated.
Tires are Part of the Suspension System
Before getting into maintaining and manipulating tire pressure, it should be mentioned that the tires are an integral part of the car’s suspension system. Having shock absorbers is great and all, but it’s the pliability of the tires that cushions the car from all the bumps in the road.
Over-inflating your tires will create a rougher and bumpier ride. It does. There is no way around that. If you decide to over-inflate your tires, you must realize that you do so fully understanding the impact it will have on the smoothness of your ride.
At the Very Least: Maintain Recommended Pressure
Every car has a sticker somewhere indicating the recommended tire pressure. Usually, it’s on the driver’s door jamb but some cars have the sticker on the inside of the trunk hatch.
It is important to keep in mind that the tire pressure on the side of the tires might actually differ from the pressure recommendation on the sticker.
The reason for the potential variance is that the tire is manufactured for a wide range of cars. The tire manufacturer does not know the size and weight of the car it will be mounted on. The manufacturer of the car, on the other hand, knows all the variables and calculates their recommendation. This is why you should always refer to the sticker on the car rather than the sidewall number.
If you do nothing else, absolutely maintain the recommendation on the sticker.
The Dangers of Under-Inflated Tires
Most people who have ever ridden a bicycle have ridden on under-inflated tires. Squishy tires make controlling the bicycle very difficult because the rim is sliding from side to side. The same is true on a car except that cars travel much faster and corner much harder. An under-inflated tire could potentially create the situation in which a quick decision cannot be realized with a quick movement.
Do you remember when all those Ford Explorers were losing control and sometimes flipping over? In every case, one of the tires exploded, which make people suspect it was the fault of Firestone. After a bunch of investigating, it was found that in almost every case, the pressure of the remaining tires was low. As a result, it was determined that the exploding tires were cased by under-inflated tires overheating and rupturing resulting in sudden loss of control. Under-inflated tires create additional friction and could possibly become so hot they weaken and rupture.
It has been proven that under-inflated tires are more prone to skidding in the rain, making stopping more difficult. At the very least, braking distance is increased. Worst-case situation: braking distance is farther than the distance to the car in front of you.
Under-inflated tires do not contact the road the way they are supposed to. This affects overall handling and tire wear. Some estimates put the impact of under-inflation as high as 25% faster tire wear.
So there you have it. If you take nothing else away from this article, please check your tire pressure once a month to make sure you are safe.
Exceeding the Recommended Tire Pressure
NOTE: This is a contested concept for the reasons explained below. It is assumed you are a mature and responsible adult capable of making decisions for yourself that affect the operation of your vehicle. If any part of this bothers you, don’t do it. Just because you read about it on the internet doesn’t mean you have to do it.
There are many people on PriusChat.com working to improve their mileage. They employ many techniques and reliably report their results. I mention this because there is substantial anecdotal evidence that increasing your car’s tire pressure can return higher mileage.
The recommended tire pressure for a 2004-2009 Prius is 42psi front and 40psi rear (42/40). The 2psi difference is explained as additional support for the engine in front. Some people increase to 45/43 and report repeatable mileage improvements. Some have gone as high as 50/48 and continued to report even better overall mileage. However, above this pressure, on real significant improvements are realized.
These results – though shunned by many – seem to indicate there is a mileage improvement to over-inflating tires. To a point.
Concerns of Uneven Wear
Many opponents to over-inflating tires use the argument that the tires will develop a bulge and develop a bald stripe along the radial axis. This was true a long time ago. Modern steel-belted radial tires, however, are reinforced in such a way that over-inflating does not bulge the tire.
Concerns of the Tires Exploding
The level to which some drivers over-inflate their tires is only a few psi. Perhaps as high as 10psi. This sounds like a great amount. But the realization that it’s intentionally a fraction of the tire’s potential is not something you will ever see advertised.
I had the pleasure of meeting an actual tire engineer at a car show. I can’t mention his name or which manufacturer he works for. To be honest, it has less to do with confidentiality and more with a horrible memory.
In our discussions, I mentioned that I had inflated my tires above the recommendations and was mildly concerned. He gave a “pa-shaw” sound and rolled his eyes. He then explained that the sidewall tire recommendation is based more on the risk of litigation than the potential of the tire. This gave me a certain level of ease.
As I look over this article, it’s clear that much of it addresses arguments against over-inflating tires. It’s just that this article only addressed potential mileage gains of over-inflating tires the comments section would light up with those very arguments. So they are pre-emptively addressed in an attempt to make it clear that I’m fully aware of those arguments and am not making blanket suggestions without realizing potential consequences.
Make sure to check your tires’ pressure every month. At the very least, maintain the tire pressure recommendations listed on the sticker in your car. If you choose to over-inflate your tires, be aware that you will experience a bumpier ride because the tires are part of the car’s suspension system. Though there are concerns of damaging tires with higher pressure, the evidence simply isn’t there to support them.
Anyone who has watched Star Trek: The Next Generation understands the futility of the sleek design of the Enterprise when compared to a Borg ship. I call it futility because someone spent a lot of time designing a sleek and aerodynamic design for a ship that will only ever travel in a vacuum, devoid of air (except, of course, when it’s crash landing on Veridian III).
My point here is that when there is no air, the cube shape of the Borg ship is equally as aerodynamic as any Starfleet vessel. Unfortunately, we do not maneuver our vessels in a vacuum; we have to deal with wind resistance and the impact it has on our fuel consumption.
Because we have to deal with air resistance, we must pay special attention to the way air flows around our cars. One thing is for sure: when a manufacturer puts a car into a wind tunnel, they don’t strap a Thule cargo carrier on the roof and a couple bikes onto the back. In order to earn the lowest coefficient of drag possible, the manufacturer tried to make their car as streamlined and “slippery” as possible. The goal is to disturb the air as little possible. Anything attached to the car will create a lot of disturbance and defeat the intentions.
In this article, we’re going to explore aerodynamics and how keeping your car free from external add-ons will make your car more efficient, improve your mileage, and save you gas money.
Let’s Geek Out on Aerodynamics for a Minute
Before we can delve into how things impact aerodynamics, we should sidebar for a minute and discuss what aerodynamics actually is. The easiest and simplest definition is that Aerodynamics deals with the way air flows around objects. As it turns out, the invisible air we take for granted does some really cool and strange things when objects are pushed through it.
For example, we don’t even consider it but when a car is being pushed through the air, the car is an object that wasn’t in that particular spot just a few second ago. So what? Have you ever pounded a nail into a piece of wood? That nail represents your car and the wood represents the air. The wood was perfectly happy at a state of equilibrium until you came along with your “I have a hammer and therefore everything is a nail” mentality. The nail is literally ripping the wood apart in the same way the car has to separate the air in order to pass through it. Nails are pointed to make it easier; clip the point off the nail and try again. The added effort required represents the wood’s resistance to a having a blunt object pushed through it. That’s visually the same thing as driving a Corvette compared to driving a Hummer.
Cars and air are different because the car keeps moving, which forces the air to collapse behind it. Air is, for most sakes and purposes, a fluid. Fluids take time to flow from one location to another. Therefore, when the air is collapsing behind the car, there is not an immediate “everything’s back to normal.” In fact, because of the car there is literally a hole in the air. Since the air cannot fill the hole as quickly as the car is moving, there is less air in the space immediately following the car, causing a zone of pressure that is negative compared to the surrounding air. This negatively pressurized space literally pulls the car backwards as it collapses. The engine is working to push the car forward, splitting the air and at the same time, fighting the pressure attempting to pull the car backwards. The goal, therefore, is to make one or both of these aspects more efficient.
All manufacturers have to deal with Aerodynamics. Some don’t care; like when manufacturing extra-large SUVs and trucks. Some spend weeks or months in a wind tunnel tweaking and tuning every last bend and curve to improve the frontal and rear aerodynamics. The goal is to split the air and return it to normal as efficiently as possible. To that end, some people are so obsessed that they render – and sometimes create – their own impressions of what a super efficient, super aerodynamic car would look like.
OK. That should be enough to get the point across. The smoother and slicker the car, the more efficiently it will travel, the higher the mileage, and the more money you’ll save on gasoline.
For a really good explanation and much more information, go to BuildYourOwnRacecar.com. This is where I got the two images from. http://www.buildyourownracecar.com/race-car-aerodynamics-basics-and-design/
Remove Things from the Roof of your Car
The roof is a great place to lug a cargo carrier, kayak, Grandma, or whatever might need to be moved from one place to another, out of sight, and without taking up interior cargo room. But when these things are no longer needed, do yourself a favor and remove them. Too many times, it’s just easier to leave the things on the roof. It makes sense because it was probably difficult to get it all strapped in to begin with and removing it will be a hassle considering you’re going to need it again at some point. But if that “at some point” is in two years when you take another family trip, remove it.
Remove Things from the Back of your Car
By now, this should be pretty obvious. Not only does the bike rack full of bikes represent turbulence, it disrupts the air’s ability to smoothly exit the back of the car. This turbulence creates eddies that increase drag. When you’re not taking your bikes to go riding, remove them from the back of your car.
Make sure your Next Car is Aerodynamic
Perhaps your current car isn’t the most aerodynamic. There’s not much you can do about that now. But you can think about the future. Whenever you’re in the market for a new car, try to make sure the new one is more aerodynamic than the one you are trading in. By doing this, you will continuously make strides towards better mileage.
The study of aerodynamics is actually really neat and if you have time, dig into it. You should try to purchase vehicles that are designed with a low coefficient of drag because they most efficiently move through the air. Mounting things to the roof and/or the back of the car interrupts the smooth movement of the air, creates eddies and turbulence, and should be removed when not in use.
Aside from our usual Faraday Future tagging, this week we cover…
Me talking about buying an electric motorcycle. Or trying to anyway.
I want to talk hyper loop.
I once knew a guy who was sure that the best idea for a restaurant ever, in the history of food service, was a Dracula themed restaurant where the menus are shaped liked bats. Yeah, that was the whole idea. He was sure it was a winner. Faraday Future thinks our future is robots. Lots and lots of robots.
First of all, I want to make it clear that this is not an article about drafting. To prove that point, let me explain what drafting is and why it’s dangerous, illegal in some places, and a really, truly, and seriously bad idea.
In auto racing, drafting is also referred to as “slipstreaming” because the goal is to ride in the slipstream of the car in front. In order to do this, the trailing car must be close enough to the leading car to stop the air from collapsing around its back. By doing this, the airflow moves around both cars as though they were one single vehicle. Since much of the effort of propelling any object goes into wind resistance, the trailing car is able to travel much more efficiently. This is shown in the following image, stolen from efluids.com.
Drafting is most beneficial at high speeds where wind resistance is great. This is why racecars draft and some people draft behind semi trailers on interstates. Drafting is rude because the trailing car is much too close to the leading car. It is also extremely dangerous because driving can be unpredictable and drafting leaves virtually no room for sudden movements or braking. To reiterate: don’t do it.
So What’s the Difference
Driving behind a large vehicle at a safe distance is similar to drafting only in that the vehicle in front takes the brunt of the air resistance. Unlike drafting, the trailing vehicle is following at a safe distance. The benefit to the trailing vehicle is that the lead vehicle has disturbed the air in such a way that it does not represent as much resistance to the trailing vehicle.
Notice in the illustration above that the air flow lines are drawn parallel to each other in what’s called “Laminar Flow”. Air is illustrated as strata – or sheets – of air that don’t interact with each other. This does a great job of showing that air is moving around the car, but this is not how air really flows. The goal of most automobile manufacturers is to perturb the air as little possible in order to make their car more efficient.
However, there are many not-so-efficient vehicles on the road such as delivery vehicles, semi tractor-trailers, etc. These vehicles have large flat backs and leave huge eddies of air as they travel. Anyone who has ever been standing on the side of the road when a semi tractor-trailer rolled by understand just how strong their wind currents can be. Depending on the aerodynamics of the truck and their speed, their wake can extend hundreds of feet. This is illustrated in the following image.
This image is probably the best to illustrate the difference between following at a safe distance and versus drafting. Someone drafting would want to be in front of the red, disturbed air, between the truck and the first marker line. Notice how the dark blue actually curls up and towards the back of the truck? This will literally pull the trailing vehicle towards the truck’s bumper. Following at a safe distance has the trailing car behind the disturbed air, in the light blue area, almost two truck-lengths away. Even at that distance, there is benefit thanks to the disrupted air.
The Other Reason to Follow Other Vehicles
Deserved or not, hybrid drivers have a stereotype of being slow drivers. Sadly, I have seen some cases in which this reputation is strongly earned. Having said that, there are times when I am on a multilane road and I just don’t feel like driving like a bat out of Hell, acting as though commuting is a competitive sport with a trophy handed out if you get to work faster. Perhaps I only want to drive a few MPH above the speed limit and have no concern with keeping up with the general flow of traffic.
Sometimes, I come upon a delivery vehicle or lawn care truck that is driving close to the speed I prefer. In this situation, I will maintain a safe following distance and stay there. There is a very good chance – like many of my phobias – that it’s all in my head, but I like to think that rather than me being the slow car now it looks as though I’m the poor car stuck behind the slow vehicle. But I don’t care because in the end I get to drive at my desired speed. This might sound like a stretch, but I was a little relieved to see a post on an online forum in which someone asked if they were the only ones to apply this technique. Multiple people admitting to it.
At a slower speed, any benefit from perturbed air is minimal if there is any at all. The primary point in following a large slow vehicle is the benefit of not feeling as though you are being pressured to driver faster than you would prefer.
Drafting is a really stupid idea and extremely dangerous. Following large vehicles at a safe distance can reap aerodynamic benefits without risking your life. Sometimes following slower vehicles gives you the opportunity to get out of the roadway racetrack and drive at a more comfortable speed.
This week our panel take on:
RAV4 Hybrid sales for April 2016-3,807. YTD 2015-8,741 2016-4,970
Prius v sales for April 2015-1,322 and for April 2015-2,462
Bye bye Prius v
Mark Coughlan talks about how Awesome the new 2G Chevy Volt is (and how awesome In-N-Out is).
This week Evan, Paul and Russell go over…
Yesterday was Earth Day: a perfect time to talk about hypermiling and reduced emissions. But I’m not going to. You see, if we really try, we can do even better than hypermiling. In fact, focusing exclusively on driving more efficiently is not always the best approach. After all, it assumes that you will always be driving. Also, there are stories about people literally driving farther than necessary just to make sure their engines warm up so they can register better mile-per-gallon averages.
Today we’re going to shift our focus from driving more efficiently and focus on driving less. There are several approaches to reducing our dependence on our vehicles. This article might not get to them all but hopefully it will serve as a good start and get you thinking.
The most obvious alternative to driving is walking. OK, I know what you’re thinking: “I live too far from work” or “I have to haul things” or whatever. Yeah, I get that. I have those things too. Walking is not an all-or-nothing alternative. The point here is not to walk everywhere all the time. The point is to know your walking speed and acceptable distance. Then, when you have to get yourself from one place to another, ask yourself whether it is within your acceptable distance. If it is, seriously consider walking.
On a more personal note, we have become a sedentary society. We sit in our car, at our desk, and in front of the television. No matter who you are or what your current state of health might be, we can all benefit from taking more steps every day.
Stepping up from walking is riding a bicycle. The same concept applies: know your acceptable distance and situations. If the current need fits your parameters, ride your bike. From time to time, someone at the local fitness center will wonder why there are so many parking spots and so few bike racks. This is a perfect example of when to ride your bike.
Not only does bicycling extend the distance and shorten the time compared to walking, mountable carriers allow for light grocery shopping. If you need to run to the local store for a few things in order to complete the recipe, don’t bother firing up the vehicle; hop on your bike.
Some of us are lucky in that we have coworkers who live within a mile or two of our homes. This makes carpooling pretty convenient. Some companies have bulletin boards where people can post interest in ride sharing opportunities. Some are actual bulletin boards in a common area such as the cafeteria whereas tech savvy companies might have information on their intranet.
When it comes to driving less, any improvement is an improvement. Let’s say you have a coworker who lives halfway between you and work. Even if you drive to their house and park your car, you are not driving the entire trip. Even if the coworker lives a few miles out of your way, the fact that you are not driving every day means that you are driving less.
Of course, carpooling means taking turns. Don’t be a carpool leech! The only acceptable exception is that you do not have a car at all.
Some people have mass transportation options and don’t even realize it. Make sure to check your community’s internet site or other information to see what mass transportation options exist.
Some people place a stigma on riding the bus or train. Their belief is that not rolling up in your own set of wheels somehow makes you less of a person or they see mass transportation as a lower form then car ownership. But these people are spending money on gasoline and potentially on parking fees. They log more miles on their car, which will result in faster wear-n-tear maintenance. They aren’t aware the amount of money they are spending just because of their personal belief.
Those who ride the train and/or bus to and from work do not have to drive in the rain or snow. They save money on gasoline and potentially parking fees. Ridding as a passenger is much less stressful than driving and provides ample opportunity to get a little more work done, sit quietly, or catch up on that podcast.
Plan your routes
Have you ever been our in your car running a few errands and realize that you’ve crossed town twice already and will need to do it again? Hopefully, it occurred to you that had you planned your errands a little better, you wouldn’t have to do so much driving around.
Not only does better planning reduce the miles you log in your car, it saves you time and money. You save time because, of course, you spend less time in your car. You save money because gasoline is not cheap.
Next weekend – or whenever – when you are about to run a series of errands, consider writing them down and then numbering them based on a preferred route. You would be surprised how much time you end up saving this way and how much better you feel for having gotten through them faster.
Reducing the miles driven in your car by any amount is an improvement. Even if carpooling and mass transportation are not available in your area, you can still find other ways to drive less by biking and walking from time to time.
Here is my biggest rub. I pulled these tips from international sources. These things are tightly integrated into the very fiber of most Europeans. Trains and buses are used to capacity and many companies have as many bike racks as parking spots. Some European companies charge their own employees for parking in their garage as a way to encourage carpooling and mass transportation. Sadly, these things are usually either ignored or rebuffed by most American citizens. I shutter to think how bad things would have to get before more people here started acting more like the people over there.