Tips
 
*If you are driving a stick shift with fuel injection, note that 50% throttle at 1200 rpm's uses less gas than 10% throttle at 2500 rpm's. As long as the engine is not lugging or pinging, shift as soon as possible and use plenty of throttle. The engine is more efficient when it does not have to pump air past a closed throttle plate.

*You could use a GPS to calculate how far away you are from the next state and if you know fuel tax is less in the next state, just put enough fuel in to get you to the next state and fill up with gas where it is cheaper

*Pencil gauges are not accurate for measuring tire pressure.
*When choosing the optimum air pressure for you tires the figure imprinted on the tire wall is the MAXIMUM.  The figures printed on the sticker in the door frame, in the fuel filler flap, and in the manual are for ''comfort'' rather than fuel efficiency. Generally speaking, a slightly higher pressure will improve fuel mileage and handling, but too high will degrade traction and wear the tires rapidly, as well as being unsafe.

*Reusable "oiled" air filters may increase gas millage because of the amount of dirt that they trap and they will allow more air to move into the engine which in turns causes a better combustion in the engine
*Most car modifications do not improve mileage. Extra wings add drag. Power improvements often hurt mileage. However, if your car is turbocharged, chiptuning may result in a mileage boost. The mileage boost will be canceled out if you drive more aggressively due to power improvements.

*Many of these tips change slightly if your engine is turbocharged or diesel. For instance, diesel engines use almost no fuel while idling. Diesel trucks will often be left idling all night to provide heat or power for the trucker inside the cab, at the cost of relatively little fuel.
*Wholesale unleaded is now a traded commodity. Watch the futures price as it will forecast price at the pump, which will be about equal to the wholesale price plus taxes plus about a nickel per gallon for the station.

*Keep meticulous records of what you spend and how many miles you drive so you can quickly spot changes in vehicle performance.  It will also help focus you on the goal of saving.

*Every MPH faster yields you less advantage than the last one.  Going 10MPH is a big difference over 5MPH, but there is very little difference between 55MPH and 60MPH, unless you are on a very long trip.  Many people mindlessly speed wherever they go, and gain absolutely nothing but a heftier fuel bill.  Assuming everything goes perfectly (and when does it?) going 5MPH, even 15MPH faster on a highway for a short trip will yield nothing but aggravation as you keep catching up to slower traffic.

*Slow down a little below the speed limit, and the highway can seem like it is wide open.

*Often the right-most lanes keep moving more than the left-most in areas prone to traffic-jams.  Vehicles continue to exit, which keeps leaving 'gaps' to fill in.

*A manual transmission saves an average $1000 on the cost of a new vehicle, and eliminates routine transmission maintenance that an automatic transmission requires (and most people never do this maintenance once the warranty is up - so a used car with an automatic is a risky purchase).  In most cases, an automatic transmission gets significantly worse mileage overall than a manual transmission.

*Neutral is also a 'gear' on a manual transmission, which you use constantly anyway.  Learn how to coast between traffic lights, applying power only as needed to keep the car rolling (more or less) with traffic.  Learn to judge terrain and use neutral to its full potential to keep the car moving 'for free', and save more gas over time.

*'Regenerative braking' recovers far less energy than acceleration requires to replace the momentum it loses.  To 'coast' further without regenerative braking excessively slowing your automatic transmission equipped hybrid, putting just the right pressure on the accelerator can prevent the 'regen' drag without adding engine power (i.e. if done right the engine won't start AND the regenerative braking won't kick in).  With manual transmission hybrids, just leave it in neutral to defeat 'regen' and coast further.

*If you are always stuck in rush hour traffic after work anyway, try to find something to do near your work until the traffic dies down, rather than try to fight through it.

*If you want more information about the mileage NOW, and your car doesn't have a real-time fuel economy indicator, there are various OBDII reader devices (like the 'ScanGauge' or 'Equus 3130') that can be plugged into cars with an OBDII port, and provide 'live' real-time information about fuel consumption rate (gallons per hour), engine RPM, speed, whatever you want that's tracked by the engine computer.  Some of them also allow the data to be recorded and downloaded to a computer with a serial or USB cable.  Some are little more than a serial/USB cable that plugs into a portable computer with software to give you all manner of 'instruments'.

*The more convenient it is to check your tire pressure, the more often you'll do it.  If you are dedicated enough to do it with a manual hand/foot pump, fine.

** You can spend a little extra on a pretty good self-contained electric one with a jump start and flashlight on it, too, and then consider it a 'safety' purchase.

** If you have a garage, an air compressor has many uses besides tires.

** If you have a larger vehicle (with higher pressure truck tires), you will need a 'real' air compressor; the little electric ones made for cars will fail right away, and you'll wear yourself out trying to pump it yourself.

 
Warnings
 
  • Don't get crazy in your search for cheaper gas stations. If your car has a 15 gallon tank and you find a station that is 10¢ cheaper per gallon, your savings is a maximum of $1.50. But if you get 20 miles to the gallon, and drove 10 miles each way to that station, you have already used one gallon of gas to save $1.50, which at $4.00 per gallon would actually be a loss of $2.50.
  • Don't put a lower or octane in your car than your car's manual states it requires. However, unnecessarily high octane is a waste of money. Octane is only a rating of the tendency of the fuel to cause damaging engine knock under extreme load conditions and all modern cars of the past decade or more must by law run well and maintain warranty compliance on regular low-octane fuel. Higher octanes are sometimes "recommended" for high performance vehicles simply because the manufacturer can cite slightly higher maximum power outputs but the engine will self-adjust to any provided fuel and even lead-footed drivers will not notice the difference between fuels if they aren't told of the substitute first.
  • Be careful of credit card interest rates which may negate your gasoline savings. Also verify that the stations you use don't charge higher prices to credit card customers
  • Stopping and starting the engine frequently will cause extra wear. Don't stop the engine if you are going to idle for less than a minute.
  • In very cold environments, it is recommended to allow the vehicle to idle and warm up, rather than just start it and take off. You might save gas, but your engine oil won't do its job until it's fully liquid, so you'll spend more money on overhauls.
  • Drafting is dangerous. All the fuel savings in the world will not matter a bit if you get wrecked while 'trying to save gas'. Safe driving habits will save a lot more money than risky driving, and maybe even save lives. Slow down. Be careful.
  • Nearly all gas-saving devices do not work, and some even decrease fuel mileage. Intake twisters, gas pills and fuel line magnets do not help mileage. Even if the mileage improvement claims were true, they often cost enough to negate any potential savings.
  • 'Chipping' the car (changing/flashing the ROM in its 'brain') is usually meant to improve power, but often fuel savings are claimed as well. Be paranoid about it. It usually can achieve the power statistics it claims, but possibly at the cost of dreadfully expensive engine and drive-train wear and damage. The wrong chip (or a buggy version of a chip) can result in a dead car that's expensive enough to repair that it's 'totaled'. Needless to say, 'chipping' a car definitely voids the warranty.
  • Be very careful when shifting into neutral when going down hills. You may find yourself going a lot faster than you thought you would. This is actually illegal in some jurisdictions.
  • Keep in mind that the engine will assist with braking down steep inclines. If you ever need to brake while going down a hill, keep your vehicle in gear. Staying in neutral and only using your brakes (freewheeling) can cause the brakes to heat significantly, resulting in brake fade or breakdown, and total loss of control.
  • Be sure to keep to right lanes if you're not going to keep up with speeding traffic, and allow other traffic to pass.
  • If you drive slowly enough on a long enough trip to add hours, be sure to take extra breaks.
  • When you sign up for the 'loyalty' cards at your nearby store, realize that they do that to track your spending for their own benefit. That is not to say that you don't get a lot out of it. The savings can be substantial.