By Edward Choi - Jul 31, 2008
How to Increase Your Car's MPG
A lot of readers email us about this issue. So how DO you save gas? We had a straightforward discussion about it, and here is what we know and can recommend.
Before we get into that...
DO NOT BECOME A VICTIM OF too-good-to-be-true SCHEMES. Yes, your car can theoretically run on water. But that's when you have a certain type of sophisticated electrical system already installed on your car. It will cost you hundreds of thousands of dollars to build this kind of car. So practically speaking, this is not currently feasible, especially not with a kit that costs only $24.99 or so.
Having said that, here are some of the tips for saving gas with your current car:
Your car will consume more gas when the engine revs more. You can tell whether the engine is revving more by looking at your tachometer (RPM gauge) or listening to your engine. Most of car engines these days are Internal Combustion Engines (ICE). These ICEs have different number of chambers called cylinders, and your car's manual will say how many and how big they are. For example, I-4 (inline-four) engine has 4 cylinders lined up in one line. V-6 engine has 6 cylinders in a v-shape format, three on each side. The total inside volume of these cylinders is the engine size, and you will notice a number like 3.0L (three liters) or 3000 cc (cubic centimeters). The larger the total volume, the more likely the engine will generate more power and consume more gas.
Your engine works by spraying gasoline into the cylinders and igniting them with a spark. This combustion generates power that pushes out a rod called piston, and as the piston pushes out, it turns a crank. As the crank turns, it pushes the rod back into the cylinder, and the piston gets into the position to be pushed out again. This completes one rotation or revolution, and the word "revving" the engine comes from this cycle of revolutions. When your engine revs more, gas is spayed into the cylinders to be burnt more quickly, and you use more gas.
These tips below are based on the fact that not all engine revs generate equal amount of distance travelled. When your car is starting from a stand still position, your car needs much more power to get going. Your tachometer will go up to four or five thousand rpm (revolutions per minute) but you may accelerate to a speed of only 20 to 30 miles per hour. When you are cruising, same amount of revs could get you twice as much speed. If you want to save gas, your goal is to maximize the distance travelled per each engine revolution.
Tip #1: Accelerate Slowly
Some say life is a race. You want to get to the next traffic light faster than the car next to you. But curving this urge will save you a lot of gas. When you accelerate quickly, you will notice that your tachometer shoots up and your engine revs a lot. You end up traveling a lot of distance in a low gear setting, and your distance travelled per rev becomes low. Not only that, you will end up getting to the next light faster and will need to brake harder as well. When you use your brake, you are throwing away all the gas you used to gain the speed.
Tip #2: "A smart driver seldom uses brakes"
That is what we were taught when we were taking high school driver's education classes. This does not mean in any way that you should not use brakes. In fact, it doesn't have a lot to do with how much brakes you use, but more to do with how well you plan each push you make on the accelerator. If you are a smart driver, you will look ahead and be easy on your lead foot if you think you may have to stop at the next traffic light. And if you drive smartly, you will make the most distance out of each rev your engine makes.
Tip #3: Don't Drive Too Fast
This tip applies especially when you are cruising on a highway. Each car has different number of gears - 4, 5 or even 6. The more gears you have, the more likely you will save gas when you are cruising on the highway. You have to study how your car's gear is programmed when you are cruising. Ideally, you want your tachometer to show a very low number, even when you are driving 50 to 60 miles per hour. If you are constantly driving faster than 60 miles per hour, you are most likely wasting a lot of unnecessary revs. Discover the right speed that your car will cruise without you having to step on the accelerator too much. Find your ideal balance between your speed and your tachometer: if your cruising speed tachometer moves from 2 to 4, you are pretty much using twice as much gas - is your speed twice as fast? By experimenting, you will find your preference and balance between your tachometer and speedometer. The right balance happens almost always below 60 miles per hour for most of the drivers. You may get to your destination a few minutes later, but you will save a lot of gas, and money.
Tip #4: Don't Tailgate
Not only it's illegal, it will also cost you more gas. That is because tailgating usually requires constant tapping on accelerator and brake paddles. If you understand the simple concept of maximizing each engine rev, you will understand why accelerating and braking can cause you to waste the precious engine revs. The best way for maximizing mpg on highways is to use cruise control. If you want the thrill of tailgating, then stick to watching the unbelievably realistic NASCAR coverage on TV these days, or just tailgating at a sporting event.
Tip #5: If It's Hot, It's OK to Use the Air Conditioner
It turns out that using the air conditioner doesn't really decrease your car's mpg. But the myth persists. Yes, we have all done it before - driving from Los Angeles to Las Vegas without the air conditioner on and with the windows down, when it was over 100 degrees outside. We thought that we were saving gas. The unpleasant body moistures and sandy air we thought were worth the sacrifice. But studies after studies indicate that it makes very little difference, if not at all, to use the air conditioner. If your car is over-heating or if you feel that use of air conditioner may harm the atmosphere, that might be a different issue. But on the topic of improving mpg, use of air conditioner is ok, and it will be in many cases better for your health. The more important factor is your car's aerodynamics. Any kind of air drag is bad for your car's mpg. Opening windows is mostly bad. The worst culprit usually is carrying non-aerodynamically designed luggage on your roof racks.
Tip #6: Use Clean Air Filters
Out of all things you can do to maintain your car properly, using clean air filters can be one of the best ways for improving your mpg. So what does the filter do anyway? Many folks think that it filters the air that goes inside the cabin for the passengers to breathe. Most of the luxury cars these days have some kind of air purification system for the passengers. But as you can imagine, clean air for the passengers to breathe would not improve your car's mpg. The filter we are talking about cleans the air for your engine to breathe. As the engine sprays gasoline inside the cylinders for a combustion cycle, it needs good clean oxygen for it to burn the fuel efficiently. In fact, the so-called "turbo charged" engines compresses the air as it delivers into the cylinders, and this process significantly improves the engine's overall performance - more power and better mpg. Using a clean air filter will not make your car turbo charged, but it will certainly improve your mpg. Decently clean filters are ok - just stop using the dirty ones.
Tip #7: Maintain Your Car!
Sometimes it feels like the manufacturers are trying to make money by recommending regular scheduled checkups and tune-ups. Car dealers certainly can make a lot of money with these regular checkups. Skepticism aside, it is natural that a well maintained machine will perform more efficiently. When you do the checkups, know your basics, or go with someone who does, if you want to avoid getting ripped off. The truth is, manufacturers try to decrease the overall ownership costs in order to be more competitive against other manufacturers, and this includes the regular maintenance costs. For example, you will notice that most manufacturers will recommend an oil change at more than 3,000-mile intervals, while the dealers or mechanics will recommend 3,000 miles strictly. Because the manufacturers are trying to decrease consumer's maintenance costs, they tend to recommend only what's necessary in order to keep the car running at certain mechanical parameters. Following their recommendation is not a bad idea for properly maintaining your car. If your car's oxygen sensor is malfunctioning, for example, your mpg could suffer by as much as 40%. If your car's tires are not properly inflated, that could also cost you 1-4%. Good quality engine oil can also add 1-2% of mpg. These little things add up, so maintaining your car can definitely help with your car's mpg.
Tip #8: Diet Plan
Lose the weight - for your car. If you are carrying gallons of water or slates of home improvement stuff that you forgot to unload from your last trip to the big box chains, then lose them. Just as you would be able to run much faster if you lost a few pounds, your car will have better mpg if you unloaded some of the unnecessary weight. It might be a stretch, but imagine if all Americans were in shape, how much gasoline we would save nationally? Or if all cars were built 10 pounds lighter?
Tip #9: Don't Idle
Treat each rev preciously. When your car is idling, every single rev is being wasted. When you are waiting in a long drive-through line and the kitchen is not moving, you should turn off the engine. Sometimes we spend over 10 minutes waiting in line, and all that revving gets wasted. If your two-year-old must listen to a song about buses going around the town while you are waiting at a drive-through, then make sure you have a good battery to run the radio. The new hybrid cars use higher voltage batteries that manage engine ignition much more efficiently. These hybrids turn the engine off when you come to a stop, and turn it back on when you step on the accelerator. Idling is a waste, so let's avoid it as much as possible. The worst kind of idling happens on bumper-to-bumper traffic jams every commuting day. Maybe going to work one hour earlier, if you can work it out, may not be a bad idea, for saving gas and improving your career track.
Tip #10: Plan Your Trips
Making several trips to run your errands has some drawbacks. It almost always forces you to drive more on the road. And worse yet, it will make your car run on colder engine more. Your engine will burn more efficiently when it is warmed up. Idling or revving your car just to warm up the engine may wipe out all the benefits of driving a warmed up car. Just don't let your car barely warm up and down and up and down as you make multiple trips on a weekend. Combining trips could also mean going to the groceries together with your neighbors. Instead of two minivans running on cold engines traveling the same road, you can have one traveling at a time. Of course, you should take turns driving, or it might become an unfair savings to one or the other.
There are plenty of ways to improve your car's mpg. If you follow all these tips, and if you were previously an offender on all counts, you could potentially improve your car's mpg by almost 25% (or more, if you include the oxygen sensor malfunction). That could potentially be thousands of dollars of savings per year. If these specific recommendations are too complicated for you, just remember to drive passively. It will save you a lot of gas. And maybe buy a more fuel efficient car next time you are shopping.
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