GasBuddy.com Top Ten Fuel Saving Tips
1 Avoid High Speeds As your speed increases, your aerodynamic drag increases in an exponential fashion. Driving 62 mph (100 km/h) vs 75 mph (120 km/h) will reduce fuel consumption by about 15%.

2 Do Not Accelerate or Brake Hard By anticipating the traffic and applying slow steady acceleration and braking, fuel economy may increase by as much as 20%.

3 Keep Tires Properly Inflated Keep tire air pressure at the level recommended by your vehicle manufacturer. A single tire under inflated by 2 PSI, increases fuel consumption by 1%.

4 Use A/C Sparingly When the air conditioner is on it puts extra load on the engine forcing more fuel to be used (by about 20%). The defrost position on most vehicles also uses the air conditioner.

5 Keep Windows Closed Windows open, especially at highway speeds, increase drag and result in decreased fuel economy of up to 10%.

6 Service Vehicle Regularly Proper maintenance avoids poor fuel economy related to dirty air filters, old spark plugs or low fluid levels.

7 Use Cruise Control Maintaining a constant speed over long distances often saves gas.

8 Avoid Heavy Loads Remove the sand bags from your trunk in the spring and pack lightly for long trips.

9 Avoid Long Idles If you anticipate being stopped for more than 1 minute, shut off the car. Restarting the car uses less fuel than letting it idle for this time.

10 Purchase a Fuel Efficient Vehicle When buying a new vehicle examine the vehicle's rated fuel efficiency. Usually choosing a small vehicle with a manual transmission will provide you with great fuel economy.

HybridCars.com Fuel Saving Tips

Create a "Work" Space
Leave plenty of room to the vehicle in front of you. If the traffic ahead slows, you will have a buffer to maintain momentum and conserve energy, allowing you to plan ahead. I use a buffer of 500-1,000 feet or more. As an added bonus, the vehicle in front of you won't be spraying gravel on your car.

Alternative Routes
Try different routes for common trips. I could use the freeway for 99 percent of my daily commute. I have learned instead to take the first 20 miles of my 44-mile trip using a parallel highway. I travel an extra mile, but this way I avoid freeway speeds and traffic while gaining 10 mpg or more.

Memorize Common Routes
If your vehicle is not equipped with a good, accurate real-time mpg- meter it will help to keep a log between fills to determine which way saves you more. Get familiar with your route—know where a little gas is required and where you can coast.

Reduce Wind Resistance by Reducing Speed
Wind resistance roughly doubles between 55 mph and 70 mph. For example if there is a constant 200 lbs fuel-robbing wind pressure at 55, then there will be more than 400 lbs fighting you going 70. As a rule of thumb, consider driving the speed limit or lower, if traffic conditions will allow.

Quality of Gasoline
I haven't noticed any performance changes from the most expensive gas to the cheapest. Use regular-unleaded if your car manufacturer suggests it.

Air Conditioning
The A/C system decrease your mileage, especially in smaller cars. If you desire savings, wait to activate the A/C button until rolling down a hill or decelerating. Otherwise keep it off. This way the momentum of the car runs the A/C instead of the fuel. Lastly, be sure the air conditioning or defroster is off while climbing a hill.

Windshield Defroster
The A/C compressor is automatically turned on, when the heater is set to defrost and the fan is set to ON. In this way, the moisture that has condensed on the windows will evaporate faster.

Normally, you don’t need to keep your defroster running and it wastes fuel. If you set the knob to defrost but keep the fan set to OFF the AC compressor will not run. With this setting, there will be a steady flow of air over the window to help keep it clear. If they begin to fog up you can briefly switch the fan to a middle-high setting until they clear, then switch the fan back to OFF.

Tire Pressure
Low tire pressure will rob you of your mpg. Every car has a door sticker in the driver side door jam, and these pressures should be considered MINIMUM. Higher pressures will give you greater savings, but at the expense of a harder ride.

Every tire has a maximum cold pressure rating imprinted on the side of the tire. You can go as high as that rating while the tire is cold (not driven for an hour) but do not exceed that maximum rating.

Beginning from a Stop
This is where you kill your mileage numbers. Accelerate as gradually as practical, gradually backing off the accelerator as you increase speed. Accelerate more slowly if there is no traffic behind you.

Climbing a Hill
Big hills are the second main mpg-killer. Try to find a different road going around the hill or you can or pick a route that doesn’t add significant distance to your trip.

Learn to drive with the load. That is, don’t maintain speed climbing hills. If you know a hill is ahead, gradually increase your speed on your approach. Try to guess the time it will take to reach the top. Also decide the minimum speed required at the top.

As you climb the hill, gradually slow down and try to time it so the minimum speed is reached near the top. If the traffic is extremely light, you can let your speed really sag. If you reach the top of a tall hill and find a short flat area that leads to another big hill, you are at a disadvantage because of your minimum speed. Accelerate as gradually as you can on the flat area—and time the next crest as you did for the first hill.

Rolling Down a Hill
Always plan ahead. If I know the decline is immediately followed by a steep uphill, I will usually begin my decent coasting (or switching to NEUTRAL—more on this later). Then, as I near the bottom, I'll add enough acceleration to gain momentum for the onslaught of the incoming hill. If the hill flows down to a long, flat road at the bottom, then keep your momentum.

Traffic
Don't drive only by how it "feels". If it seems like you are slowing down, don't just blindly push the accelerator down. I find that it is a difficult habit to break. Only use enough fuel for the task required. Don’t just “Gas it”, no matter how much or how little. Have a reason.

Listen to traffic reports on the radio. If you hear of a backup, go around if possible.

Additional Tips

If waiting in a line (fast food, etc.) set your parking brake and put the shifter into neutral. Turn the key one click to turn the engine off (provided that you do not need A/C, defroster, etc.).

If you need the fan, radio, etc., then click once to on again, but do not restart the engine until the line you are waiting in has moved at least a cars length. Don’t just let it idle while stopped. However, the stopping-restarting, stopping-restarting again is not recommended while in traffic due to starter wear.

If waiting at a light and the car ahead of you "creeps" ahead a few feet, do not follow. Stay where you are.

If your route uses a toll booth, get a cruising pass. That way you don't have to stop and fight traffic.

Keep your car's momentum, even around corners if it can be done safely.

Try to time traffic lights so you can cross without stopping. Approach the light more slowly to help be more successful in timing.

When you get into the car and start it, don't waste time. Don't just stay parked to let it warm up. Buckle up, get in gear, and get going.

Allow extra time to accelerate when the engine is still warming up. Your engine is a fuel PIG for the first 5-20 minutes.

Some people are putting Mobil 1 Trisync oil into their cars and gaining mpg.

Keep the oil level on the full mark, not above or below. Change your oil frequently.

Keep the tire alignment maintained.

Have a clean air filter.

Keep in mind that on a flat, level road a vehicle gets its best mpg, while just maintaining a constant speed between 40-50 mph.

For a quick boost in mpg while coasting down a long hill, you can back off the accelerator and put the transmission into neutral and let the engine idle. The longer distance you roll while in N the more dramatic your savings will be. This is a good time to switch on the A/C if you are working the button to conserve fuel.

Especially good judgment must be used in this case. You can crash so extreme caution must me made. Maximum speed while rolling should not exceed 40 mph, and on familiar roads where it can be done safely—not mountain passes while traveling on your family vacation.

Be sure to raise the engine's rpm by stepping on the gas a little to about 1.5-2K rpm before re-engaging the transmission. That is called "Rev-Matching" and will prevent transmission strain. If your shifter is located on the steering column—not in a console—I'd avoid this procedure. Column shifters can be difficult to move accurately.