( 
)
First off, i'll go ahead and get this out of the way, because most articles say it at the end as some kind of "surprising" punchline -- fuel economy depends greatly on driving style. That being said, here are a few ways you can increase fuel economy above and beyond just changing the driving style. Also be sure that the car is properly maintained and tuned up - spark plugs, air filter, fuel filter, PCV, etc.
One comment about driving a car with a manual transmission. Shifting at a relatively low RPM with a large throttle opening will help fuel economy, this is because any partial-throttle position is restricting airflow and making the engine work harder to breathe. Having the accelerator depressed about 2/3 is the most efficient. Any further and the engine computer will start adding additional fuel to the intake air to increase power and sacrifice economy. Be sure not to lug the engine, if the engine lugs you'll probably notice as its not usually a pleasant sound or feeling.
Tire pressure has a huge effect on fuel economy. Higher pressures reduce rolling resistance and thus return better mileage; obviously though you should not go higher than a manufacturer's recommendation in most cases. One notable and notorious exception is the Ford Explorer, which I can speak from firsthand experience. The recommended tire pressure is 26 psi, far too low for a vehicle weighing almost 2 tons. 26 psi is also the recommended tire pressure on my 1986 Honda CRX that weighs half as much. Ford actually issued a bulletin that asked owners to increase tire pressure to 30 psi because of the whole Firestone fiasco (which, by the way, ended up being a problem with that specific Firestone tire -- not a fault with the Explorer's design). Even 30 psi is too low, in my opinion. To avoid overinflating tires, you can put some chalk on the tire and see how evenly it wears off. Overinflated tires will wear more in the center, underinflated will wear at the edges. This is a good guideline if you want to maximize both road handling and fuel economy, but under no circumstances should you exceed (or even approach) the tire's maximum pressure, listed on the sidewall.
Different brands and models of tires can have an effect as well. Every tire has a different rolling resistance and some are definitely better than others in this respect. Often high-performance tires trade rolling resistance for improved traction. Rolling resistance is not listed currently on tires but can have a big effect on fuel economy. Most new OEM tires are low-rolling resistance, especially hybrid vehicles. There are different types of tires as well, such as all-terrain, all-season, and summer types which offer different characteristics. All season tires generally offer the best rolling resistance but neither offer the durability of all-terrain tires or the performance of a summer tire. Some vehicles recommend against changing tire types so check to make sure you can before you do.
Performance chip upgrades that modify the air/fuel mixture going into your engine sometimes can have a beneficial effect on fuel economy. I have not tried one of these firsthand but, as in the case of the Explorer, some owners have reported fuel economy gains between 10-20% due to overly conservative fuel mapping from the factory. Your luck will vary greatly on the particular vehicle you have, but there are many chips available. These can range in price from around $200 -$500. Avoid the +20 hp upgrade modules being sold in eBay for a few bucks, these will make your engine run too rich, probably make it fail emissions and foul plugs, and will waste fuel. These modules are just a resistor that tricks the engine into thinking the incoming air is colder (and thus more dense), so the computer adds additional fuel to the intake charge.
One of the best ways to increase fuel economy is using synthetic fluids. Synthetics have enhanced lubricating properties that offer less resistance than regular fluids. Engine oil is a logical first fluid to replace -- just ask for synthetic when you take it in, or buy synthetic at the store. A good synthetic oil will cost around $5 or $6 a quart (Mobil 1). Manufacturers claim that synthetics also increase horsepower. I have not noticed a difference. Be warned that an old engine that burns oil will burn through synthetics more quickly than regular oil.
Don't stop at just the motor oil, though. Transmissions and differentials can also benefit from this, and even wheel hubs. Just be sure to get the right kind.
Large wheels and tires add drivetrain inertia and will reduce stop-and-go fuel economy, and probably jeopardize handling in the process. Standard size alloy wheels are generally the lightest but even a steel wheel is lighter than a 22" chrome spinner.
On trucks and SUVs adding an airdam under the front bumper can improve aerodynamics. Some trucks already have one; obviously an airdam that is too large will comprimise ground clearance and probably not look the best either. If you take a look at a 2007 Chevy Silverado, it has a large flexible-rubber airdam in the front, you probably could find a similar material at a hardware store and make it yourself. If ground clearance isn't as much as an issue, there are some spoilers that fit under the bumper that may help as well.
High-performance intake systems and exhausts may help to some extent because the engine is breathing easier, but don't expect a huge improvement.
Avoid all "fuel saving devices" (I cover these in a separate guide) as not a single one has been found to work. Trust me, if there was a magic device that worked, the automotive giants would be ALL OVER them. On a similar note, using premium fuel in a vehicle that doesn't need it will NOT help fuel economy. The only "fuel saving device" that does any good is cruise control, as it can maintain constant throttle positions much better than any human ever could, and this improves fuel efficiency. Some vehicles without cruise control can be retrofitted with one.
Adding acetone to the gasoline has been a common idea to improve fuel economy. I have heard a mixed bag of reviews on doing this - some swear it works, most say it doesn't, and many say that it is dangerous because it burns hotter than gasoline alone. If it really did work and was entirely safe, I'd imagine that it would make it way into all gasoline.
If you have any other tips that I have not listed, let me know. Shoot me an email at siegetanked@yahoo.com.
Thanks for reading.
-J
One comment about driving a car with a manual transmission. Shifting at a relatively low RPM with a large throttle opening will help fuel economy, this is because any partial-throttle position is restricting airflow and making the engine work harder to breathe. Having the accelerator depressed about 2/3 is the most efficient. Any further and the engine computer will start adding additional fuel to the intake air to increase power and sacrifice economy. Be sure not to lug the engine, if the engine lugs you'll probably notice as its not usually a pleasant sound or feeling.
Tire pressure has a huge effect on fuel economy. Higher pressures reduce rolling resistance and thus return better mileage; obviously though you should not go higher than a manufacturer's recommendation in most cases. One notable and notorious exception is the Ford Explorer, which I can speak from firsthand experience. The recommended tire pressure is 26 psi, far too low for a vehicle weighing almost 2 tons. 26 psi is also the recommended tire pressure on my 1986 Honda CRX that weighs half as much. Ford actually issued a bulletin that asked owners to increase tire pressure to 30 psi because of the whole Firestone fiasco (which, by the way, ended up being a problem with that specific Firestone tire -- not a fault with the Explorer's design). Even 30 psi is too low, in my opinion. To avoid overinflating tires, you can put some chalk on the tire and see how evenly it wears off. Overinflated tires will wear more in the center, underinflated will wear at the edges. This is a good guideline if you want to maximize both road handling and fuel economy, but under no circumstances should you exceed (or even approach) the tire's maximum pressure, listed on the sidewall.
Different brands and models of tires can have an effect as well. Every tire has a different rolling resistance and some are definitely better than others in this respect. Often high-performance tires trade rolling resistance for improved traction. Rolling resistance is not listed currently on tires but can have a big effect on fuel economy. Most new OEM tires are low-rolling resistance, especially hybrid vehicles. There are different types of tires as well, such as all-terrain, all-season, and summer types which offer different characteristics. All season tires generally offer the best rolling resistance but neither offer the durability of all-terrain tires or the performance of a summer tire. Some vehicles recommend against changing tire types so check to make sure you can before you do.
Performance chip upgrades that modify the air/fuel mixture going into your engine sometimes can have a beneficial effect on fuel economy. I have not tried one of these firsthand but, as in the case of the Explorer, some owners have reported fuel economy gains between 10-20% due to overly conservative fuel mapping from the factory. Your luck will vary greatly on the particular vehicle you have, but there are many chips available. These can range in price from around $200 -$500. Avoid the +20 hp upgrade modules being sold in eBay for a few bucks, these will make your engine run too rich, probably make it fail emissions and foul plugs, and will waste fuel. These modules are just a resistor that tricks the engine into thinking the incoming air is colder (and thus more dense), so the computer adds additional fuel to the intake charge.
One of the best ways to increase fuel economy is using synthetic fluids. Synthetics have enhanced lubricating properties that offer less resistance than regular fluids. Engine oil is a logical first fluid to replace -- just ask for synthetic when you take it in, or buy synthetic at the store. A good synthetic oil will cost around $5 or $6 a quart (Mobil 1). Manufacturers claim that synthetics also increase horsepower. I have not noticed a difference. Be warned that an old engine that burns oil will burn through synthetics more quickly than regular oil.
Don't stop at just the motor oil, though. Transmissions and differentials can also benefit from this, and even wheel hubs. Just be sure to get the right kind.
Large wheels and tires add drivetrain inertia and will reduce stop-and-go fuel economy, and probably jeopardize handling in the process. Standard size alloy wheels are generally the lightest but even a steel wheel is lighter than a 22" chrome spinner.
On trucks and SUVs adding an airdam under the front bumper can improve aerodynamics. Some trucks already have one; obviously an airdam that is too large will comprimise ground clearance and probably not look the best either. If you take a look at a 2007 Chevy Silverado, it has a large flexible-rubber airdam in the front, you probably could find a similar material at a hardware store and make it yourself. If ground clearance isn't as much as an issue, there are some spoilers that fit under the bumper that may help as well.
High-performance intake systems and exhausts may help to some extent because the engine is breathing easier, but don't expect a huge improvement.
Avoid all "fuel saving devices" (I cover these in a separate guide) as not a single one has been found to work. Trust me, if there was a magic device that worked, the automotive giants would be ALL OVER them. On a similar note, using premium fuel in a vehicle that doesn't need it will NOT help fuel economy. The only "fuel saving device" that does any good is cruise control, as it can maintain constant throttle positions much better than any human ever could, and this improves fuel efficiency. Some vehicles without cruise control can be retrofitted with one.
Adding acetone to the gasoline has been a common idea to improve fuel economy. I have heard a mixed bag of reviews on doing this - some swear it works, most say it doesn't, and many say that it is dangerous because it burns hotter than gasoline alone. If it really did work and was entirely safe, I'd imagine that it would make it way into all gasoline.
If you have any other tips that I have not listed, let me know. Shoot me an email at siegetanked@yahoo.com.
Thanks for reading.
-J
Guide created: 11/15/06 (updated 07/25/09)
Thank you for voting. If your vote meets our 
