1 - Tire pressure:

Low tire pressure increases fuel consumption and is creates a safety risk because the vehicle is less responsive and more prone to get flat. The recommended tire pressure range for each car model is indicated in the inside panel of the driver door. Tire pressures should never be below the indicated pressure. Preferably, it should be 10-20 percent higher than this value. However, this may affect the ride comfort, so it is best to try and find the best compromise between the two as it may vary from car to car and road conditions. Tire pressures should be checked regularly.

2 - Ventilation and air-conditioning:

Up to around 50 mph, it would be better to cool the car by opening the windows a bit (a few inches) which would not have a major effect on the fuel consumption. At higher speeds, closing the windows and using the fan would be better. If this is not enough to cool the cabin, then, the air-conditioner may be used but at a moderate level. This means, for example, in manual air-conditioners, the temperature setting should not be at full cold (blue) but towards minimum blue (as conditions allow). In automatic air-conditioning, the temperature should be set to 72-80 °F, depending on the weather. The key is to find the highest temperature that is not uncomfortable, instead of using maximum cooling. This would save fuel. Opening the windows and doors to cool the car in a hot day before setting off would make it easier for the air-conditioning (and for you) during the journey.

3 - Selecting the right gear:

While driving, the highest possible gear should be selected while taking into account the characteristics of the engine. The key here is to keep the engine the lowest RPM range it can run without protesting. See the "RPM range" below for details.  Of course, conditions like the load level, going uphill or downhill should also be considered in selecting the right gear. Changing gear at the right time lowers fuel consumption. For automatics, you can hint at the gearbox computer to shift up earlier by lifting your right foot a bit from the accelerator pedal. Or, in some auto boxes, you can manually select a higher gear.

4 - Going uphill and downhill:

Going uphill requires much more fuel than going at a flat road. In order to minimize the losses at uphill sections, the speed should be increased a bit before the uphill section and the position of the accelerator should be kept fixed although the speed may go down a bit (as much as possible). Trying to keep the speed constant at uphill sections would require more pressure on the pedal and would consume much more fuel as a result. After the momentum is lost, try to find the right gear at which the vehicle goes comfortably without too high or too low RPM. When going downhill, if the incline is steep enough, selecting a gear in manual cars makes the fuel consumption zero. Under these conditions, engine realizes that it does not need any fuel to run and cuts it completely off. This is valid for both the gas engines and diesels. Depending on the downhill incline and the traffic conditions, a higher or lower gear could be selected to regulate the speed. In automatic gearboxes, a lower gear could be selected manually to use engine braking and save fuel.