Vehicle Fuel Saving Tips

listed in best Bang-4-the-buck order:
100% ride a bike
50% Carpool
3-15% Tire pressure to 36psi; amount of fuel mileage savings is in dispute but air is free.
15-35% Add Acetone to your fuel; 29mL/40L (2 oz/10 gal) my tank is 70L, see here $6/400ml Canadian Tire
0-10% Tuneup; check/change plugs, air filter & fuel filter; NGK G-power plugs recommended by Andy, Owner of Woodstock Imports, Dundas & Vanstart
2%-5%? oil treatment for +economy&power. Anything with PTFE (Teflon) as it's main ingredient? Ecomodder.com forums recommends: Tufoil, Auto-Rx
3%-10%? Fuel treatment; cleaning the fuel injectors will allow better fuel mixing. $3.50 STP @ Canadian Tire; Ecomodder.com forums recommends: Lucas Upper Cylinder Lubricant & FEC., FP60 by LubeControl, SeaFoam
2%-5% Torco or Amsoil 0w-30 Synthetic Motor Oil. $8/L but generally increase mileage, protection and need to be changed less. Walmart Tech2000 0w30 is $5.66/L or $22.64/4.4L
0-15% Fuel warmer; an extra piece of fuel hose that runs along the rad hose. The warmer fuel vaporizes more completely. Works better in cold climates.
2-5%? Taller tires; simple math here, the taller the tire the greater it's circumference, the farther it pushes the vehicle forward with each rotation. This essentially changes the final gear ratio. Note it will decrease your power while increasing fuel economy and it may put your speedometer out by a few kph. see calculator
5% low rolling resistance tires; wait until the tires need changing
3% Get aerodynamic, smooth wheel covers can add 1mpg
2% efficient ECU updates

Driving Habits:
Windows up; windows being down increases your drag especially at highway speeds.
A/C; i have read that A/C affects your mileage very little but my experience shows otherwise. I leave it off for in-town driving where i am accelerating often.
Accelerate slowly and evenly;
Plan routes that don't take you through stop & go traffic.
Clean out your car; unnecessary weight will cause you to use more gas each time you accelerate.
Don't idle; nuf said
Buy gas in the morning; gas is measured by volume; in the morning when the gas is still cool you get more.

Make sure nothing's a-miss:
check your plug wires; should be less than 20 Ohms. Mazda stock wires 13.5 Ohms 38 inches
If your fuel mileage is far below the manufacturers spec get a mechanic to check your O2 sensor
after a long drive feel your rims, if they are hot you may have dragging brakes / wheel bearing
Trucks; get a bed cover, cap or flow thru tailgate

Myths/Unproven:
20% Hydrogen injection; this is a SCAM ... i still might try and build my own. see IFIE
too much hydrogen can cause Hydrogen embrittlement
EFIE; fuel injected vehicles have Oxygen sensors that mis-read O2 in the exhaust as too lean fuel mixture. An EFIE compensates. or here see also Lean Burn
Mothballs; Napthalene WILL increase the the octane in your fuel and reduce ping; a timing advance is required to increase gas mileage. The ECU can adjust timing but the range is likely too narrow to make a difference; range depends on the vehicle.
?% Wrap your O2 sensors with aluminum foil held in place with copper wire, The goal is to fool the car's computer into sensing too warm a sensor so it adjusts with a slightly leaner mixture and possibly a slight advance in timing. see here
Air warmer/cooler; for every 1degree you cool the air you can add 1hp. I get differing stories about how to increase mileage.
Performance Air intake; is larger and smoother, no proof it increases efficency/mileage.
High Flow filters; beware of high flow filters that allow larger particles into the engine.
Thinner tires; careful with this one, less surface contact with the road = less rolling resistance but it also means that your braking distance may increase. Your cornering may also suffer.
0% Magnets on the fuel line; Ftc has dis-proved this so don't bother.
0% Air intake vortex; a ring with fins pointing in that sits in your air intake and swirls the air, mixing the fuel better, unconfirmed results
HyCo; a fuel vaporization chamber. More fuel gets burned in the engine and less in catalytic. Popular Mechanics tested and disproved purchased devices.
Water injection; some say this is because of expanding steam; but i have to wonder if this is not just getting colder & more dense intake air; PM disproved, its possible but nothing on the market makes a measurable difference.

Unknown:
195 degree thermostat
dimpling like a golfball
smooth hubcaps
belly pan for more aerodynamic undercarriage
Key off, then Park - automatic transmission only; You will save a small of gas by slightly changing your shutdown procedure. When you park turn off the ignition before shifting into Park and setting the parking brake.

37. Avoid using heater until the engine has warmed up
Always avoid using the heater until the engine has warmed up to its optimal operating temperature. Running the heater fan before your engine is properly warmed up will slightly increase warm-up time and increase the amount of gas you use.

48. Look well ahead & anticipate
Driving safely and efficiently relies on you being able to anticipate changes wherever you are driving. The way to achieve this is by being vigilant and constantly looking ahead.
Driving in the city you really should know what's happening at least 10-15 seconds ahead, and on the freeway that should be at least double.

60. Listen to calm music
Slower paced music is more relaxing and tends to promote a more sensible driving style while reducing stress.

79. Avoid stopping completely
Try to avoid coming to a complete stop if possible and of course when it is safe and legal to do so. It takes much less energy to drive off in a vehicle when it is already moving, even if it is only moving a few miles per hour, than it does from a complete stop.

80. Where you can take shortcuts
Sometimes you can nip rather cheekily through corner parking lots, side streets, or alleyways to get around having to come to a stop at an intersection or behind another vehicle do this and you will get to where you are going sooner and save gas, just be alert to very opportunity.
And as usual we must stress don't break the law, that is usually more costly than bad gas consumption.

81. An open cooler box
Pop your cooler box into the freezer over night and then leave it on the floor of the car, it will help reduce the temperature in the car if there are a few bottles of water defrosting you get a nice cool bonus, and an alternative to running your A/C unit.

84. Cycle your A/C
If you have to use the A/C unit, set the airflow to re-circulate then manually turn the A/C on and off as needed.

91. Empty your trunk
The additional weight you carry in your vehicle doesn't ride for free. It takes energy to move it around. Removing unnecessary stuff from your vehicle saves gas.

92. Remove unused roof racks
If your vehicle come with a roof rack and you don't use it, remove it. The same holds true for bike and ski racks. Doing so will reduce aerodynamic drag, resulting in better gas economy.

[b]98. Neutral when stopped - automatic transmission only[b]
Shift automatic transmissions to neutral when stopped, assuming you're going to leave the engine running. If you leave the transmission in drive the engine will attempt to move the car forward (creep) while being held back by the brakes, this just wastes gas.

use your block heater

Drive with you lights "off" during the day
most newer cars have daytime driving lights, don't turn on your night-time lights for day driving.

178. Upshift coaxing - automatic transmission only
Some automatic transmissions can be coaxed to upshift sooner when accelerating by gently easing of the gas pedal and then gently reapplying pressure and continuing to accelerating.

187. Burn and coast
Use a technique know as Burn and coast or pulse and glide rather than maintaining a constant speed, where practical, by using the gas pedal briefly and letting momentum or gravity do the rest you will get better gas figures.

201. Use Eco tires
If you are replacing tires then consider some of the newer 'Eco' tires that are designed specifically to increase fuel efficiency.

cover grill for winter; more aerodynamic; don't need lots of air flow in cold weather.

Carb Medic from Gunk can raise mileage when 3 oz. are used with 2 oz. of acetone per 10 gallons of gasoline

insulate the bottom radiator resivoir; the Toyota Prius has a thermos it pumps the coolant into

Lots more info here

Throttlebody spacer here

window tint -A/C doesn't have to work so hard