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Get better gas mileage
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Get better gas mileage - improving your fuel economy
Get better gas mileage - improving your fuel economy
They used to say that you could only rely on two things in life - taxes and death. Not true. There'rethree things. Taxes,death and the cost of petrol spiraling forever upwards. So consider this page your guide to making the best of a bad situation. Follow these tips and you should be able to improve your mpg - miles per gallon. Better fuel economy = more money in your bank account.
First things first: measuring your gas mileage
It seems obvious but a lot of people just don't know how to measure their average gas mileage. Fuel economy is a total mystery to them. So bear with me - I realize to a lot of you this is the age-old adage of teaching you to suck eggs.
So - a lot of cars nowadays have an mpg readout that you can select from their onboard computer. Whilst these are useful,they do tend to be a bit optimistic. I've found over the past 6 to 8 years that on-board mpg displays tend to over-read by about 7%. Not much but enough to give you a skewed view of reality. So how do you measure your average mpg? It's easy. You need to start with a full tank and always fill your tank to the point where the pump cuts off. It's painful to your wallet,especially at today's prices,but it's the best chance you have.
So first - fill up. Fill your car to the point where the pump cuts off and zero your trip counter. Now you know you're starting from a 'full' tank. I say full because each car has a different amount of dead space at the top of the tank and in the fuel filler neck,but if you let the pump cut off on its own each time,it will generally fill to around the same level each time.
Next time you fill up,again fill the tank to the pump cutoff and importantly,make a note of the number of liters or gallons you put in,and the trip counter reading. Divide one by the other and you get either miles per gallon (mpg) or km per liter. Zero the trip counter again and keep a note of the mpg calculation.
Each time you fill up,fill it to the pump cutoff,and make a note of the amount that went in and the trip counter reading,calculating your mpg or liters per km each time.
Once you have four or five calculations,you can start to figure out your running average using some simple math,or an online mileage tracker like  or . Below is the ongoing tracker for my current vehicle.
New car or something else?
One of the first things that people think of once they think they're getting bad gas mileage,is buying a new car - not necessarily brand new - perhaps a more fuel-efficient used one or even a hybrid. But be careful - you have to do your homework here. Take into account how much you could sell your existing car for and how much you're going to pay for the new one. It's important because generally speaking,going this route will normally result in a net loss - you'll end up losing money unless you keep the new car for 5 years or more. Better fuel economy will mean that the day-to-day running expenses will be less once you've got the new car. But think about it - the initial outlay to swap cars will likely be huge.
So then you're left with the other option - getting better mpg out of your existing car. In order of ease-of-attainability then,the  ten tips for better gas mileage:
1. Your right foot
So simple anyone can do it. If you're caning it away from the traffic lights,you're wasting petrol and your mpg will be down. If you're endurance racing at 80mph on the motorway,you're wasting petrol. Here's the thing - your gas mileage can drop off as much as 15% between driving at or below 65mph and driving above 65mph. Now I love speed as much as the next person but you have to be realistic here - do you want better fuel economy or to get there marginally quicker? I sound like a total wet blanket telling you this of course,but driving slower absolutely will improve your mpg. Why? Because once you get over about 65mph,you're using more engine power to overcome drag,which means consuming more petrol to do it.
What about when you're not on the motorway? Well consider a little less braking if you can. If you can see the next set of lights ahead of you are red,don't race up to them and come to a complete stop. Try to moderate your speed a little if you can do it safely. If you can get there as they turn green and the traffic in front begins to move,you're doing OK. That's because it takes more energy to get you going from a complete stop than it does from a slow roll. So if you can do this,it will improve your mpg.
lower your octane
2. Change octane if you can
Too many people drive around with medium or premium gas in their tank when they just don't need to. If your owner's manual says"regular",it means it. Putting mid-grade or premium in is just wasting money. Why? Unless you have a high-compression engine which could be prone to detonation (pinking / pinging),you have absolutely no need for high-octane petrol. The only thing that higher octane gives you is less probability of detonation. In high-performance cars with high-compression engines,which means allowing the engine management system to work at peak efficiency but for probably 75% of you,your car will quite happily run on the cheapest petrol you can put in it. Not an improvement in fuel economy per se,but a money saving at least.
3. Use the internet
Again - not so much about improving your mpg as saving money;no matter where you live,there will be one or more internet sites that can provide you with petrol prices in your area. Vote with your money. Buy from the cheap ones,and shun the expensive ones. It's not improving your mpg,but it is saving you money,and in the long term,that's what counts here. Apathy in this area is what the petrol companies rely on. To get you going,here's a couple of examples. US petrol  petrol prices. For others,use your favorite search engine.
4a. Check your tire pressures
This is a total no-brainer. Check your tire pressures regularly - make it part of your Sunday routine or something. All motoring sites and magazines tell you the same thing and that's for a reason. If your tire pressures are low,you will be increasing the rolling resistance of the tire on the road and that will be robbing your fuel efficiency - your gas mileage will be down. So make sure they're up to manufacturer recommended values (at the very least) and watch your mpg get a little better.
4b. Get low rolling-resistance tires
You might never have considered this,but manufacturers do make tires designed for low rolling resistance. This means that there's less effort required to roll the tire along the road surface. Less effort means less load on your engine. Less load means better mpg. When I went for aftermarket alloy wheels and tyres on my Honda Element,my gas mileage dropped by about 1mpg due simply to the change in tread pattern of the tires.
get rid of the roof box
5. Get rid of the roof rack
You go biking or skiing at the weekends. Great. When you're commuting to work,that empty roof rack is adding aerodynamic drag to your car. More drag means more power to overcome it,which means worse mpg. Take it off when you're not using it. Same goes for those 'aerodynamic' roof boxes - if you're not using it,get rid of it. Yes they look aerodynamic but the fact of the matter is they do induce drag. And to be honest,they look silly. Hey - I know it means getting up and doing something rather than just routinely getting in your car and driving off but we're talking about gas mileage here. mpg. Fuel economy. It's all to do with money. Be lazy? Or save money?
6. Change your air filter
Out of sight,out of mind. I'm guilty of this. Your air filter is what protects your engine from ingesting all the dust,dirt and crap in the air. If it's doing its job well,it will clog up,much like the bag of a vacuum cleaner. Once it clogs up,your engine has a harder time sucking air through it. To compensate for the reduced airflow,the engine management system will richen up the mixture,using more petrol to keep the engine running smoothly. Replace your air filter once a year and you'll guarantee better gas mileage. So why am I guilty of this? At the time of writing I change the three-year-old filter in my car and my mpg jumped by  overnight. On my car that equated to a 13% improvement for an outlay of $14. Duh! This is one of the easiest ones to do yourself too. Go out to your local parts store and look through their catalog to find the right filter (or use any of a myriad of online retailer who normally have better prices on aftermarket and performance stuff like K&N air filters) OBD Tool. It will normally be a simple matter of some plastic or metal clips to get the air box apart and then you can replace the old duffer with the new hotness.
7. Change your oil and oil filter
Whilst you won't see any massive improvement by changing your oil and filter,you're ensuring that your engine is keeping its 'fresh blood'.
8. Get new spark plugs
Spark plugs work in an incredibly hostile environment. If you've got more than 30,000 miles on yours,change them. Fresh plugs that aren't covered in carbon deposits will certainly help you in your quest to become a fuel miser.
9. Ultrasonic cleaning for your fuel injectors
The only surefire way to clean your fuel injectors is to have them removed and given an ultrasonic bath. This is like those jewelry cleaners you might have seen. Basically it's a small tub filled with detergent solution that is hit with ultra-high frequency vibrations or sound waves. The net effect is that any carbon deposits are shaken off the fuel injectors. Clean injectors give a more even fuel-air mix which results in a more predictable burn in the cylinder,which will contribute to improved gas mileage. If your injectors have never been done,or you've got more than 60,000 miles on them,consider getting the professionally cleaned. It won't be cheap but it's cheaper than a new car (by a huge margin) and it will help your mpg.
10. Remapping your ECU - chipping and tuning
Expensive one this,but it might be worth investigating. For the most part,chipping or remapping your engine management computer would normally be done to improve performance. It is possible however to go the other way - trade off some performance in exchange for better gas mileage. Not a lot of places are advertising this yet but as the price of petrol continues to spiral,I wouldn't be surprised to see this happen. For example,a few tuning houses in America have seen some interesting results from flashing European engine maps into US vehicles. It's a bit dodgy because it means those vehicles won't pass the emissions tests Car Diagnostic Tool,but if you're serious,you could get a dual-map system. For the inspection and emissions,leave it in"US"mode. For everyday driving,use the European map. Of course you didn't get that idea from here :-)
What does all this add up to?
Realistically,if you religiously stick to the above points (from a regime of previously doing nothing special),you should expect to see an mpg improvement of about 15%. Doesn't sound like a lot? Let me put a number on it. Last year I spent around $2600 on petrol throughout the year. A 15% improvement in gas mileage correlates to a 15% decrease in outlay to fill my car. In my case about $400 a year. How useful is that? It's a round trip to Vegas (no hotel). 6 months car  weeks grocery shopping. And so on and so on. So you can keep wasting money if you like,but if you're serious about getting better gas mileage,these simple steps really will help.
Happy motoring,and I hope you see some improvements in your fuel economy.
Oh - and if you're interested,send me your ideas. After my initial blog post,I had some good ones come back straight away so on page 2 you'll find the expanding list of reader-submitted tips.

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