Gas mileage refers to the ratio between how many miles were traveled and how much gasoline was burned. In some references, gas mileage refers to fuel economy or thermal efficiency, and is associated with fuel efficiency. Gas mileage measures the ability of transforming the energy stored in the fuel into kinetic energy. Gas mileage can be expressed in two ways, either fuel amount per distance (L/100km) or distance per fuel amount (km/L). In fuel per distance, if the value is less, then the vehicle is more economic. However, in distance per fuel, if the value is high, then the vehicle is more economic.
Gas mileage has importance in many aspects. Increase in gas mileage means an increase in your savings. You can cut down your expenses on fuel if you make sure that every amount of gas in your engine actually gives you the maximum distance. Also, by maximizing your vehicle fuel, you are helping the country save up on its oil reserve. If every vehicle owner will start saving up on their fuel, the country will become more independent from expensive oil imports. Oil is a non-renewable energy source, so we all must do our part in oil conservation.
Speaking of environment, being conscious of gas mileage also helps the environment. Burning fuels like diesel and petroleum cause air pollution and world climate change, while spills from oil refineries and transports pollute the waters. With all these harmful effects to the environment, we all must do our part in ensuring that gasoline is used purposely.
Gas mileage has so much to do with how much energy is stored in a particular fuel. The more energy the fuel has, the more gas mileage the fuel offers. Diesel has the highest energy content, which is at 40.9 MJ/L, among other fuels. This explains why diesel gives higher fuel economy.
Gasoline, on the other hand, has lesser energy content and gas mileage, compared to diesel. Gasoline has 32 MJ/L which results in a considerably high gas mileage. Gasoline is the widely used fuel around the world, but has been flocked with so much controversy over the decades because of continuously increasing price in the world market, high demand in almost every country, and the monopoly in the supply, excluding the politics that surround the industry of oil.
However, in recent years, studies have lead to the discovery of alternative fuels, specifically biofuel and ethanol. This is predicted to lessen the world's dependence on oil imports which, aside from oil being expensive and scarce, also raises major health and environment concerns.
Compared to gasoline and diesel, the gas mileage in ethanol is the least. Ethanol only has 30.40 energy content, which yields about 34% less gas mileage than gasoline. Because E85 fuel only has around 80% of the energy of gasoline, full usage of the said fuel alternative remains to be in question. Certainly, the lack of energy content in E85, which accounts for the two percent to 30 percent loss in gas mileage, is not to be discounted especially by the public. Also, it has been observed with fuel combination, gas mileage drops as there is less gasoline present in the fuel mixture. Taking a look at gasohol, which is a mixture of 10% ethanol and 90% gasoline, energy content is at 28.06 MJ/L. If you will compare this E85, which is a mixture of 85% ethanol and 15% gasoline, energy content is lesser as the ethanol content is much higher than the gasoline. Now, you can only imagine how less the energy content is in pure ethanol. E100, which is the pure ethanol fuel, only has 19.59 MJ/L energy content. This is way far behind the 29 MJ/L energy content that pure gasoline gives, hence using pure gasoline yields more gas mileage.
But some researchers are already finding means to increase gas mileage in ethanol. One method seen is improving vehicle engines designed for ethanol fuels. Some manufacturers have advised people to get a good E85 vehicle which gives the best gas mileage with the minimum energy content from E85 fuel combination. In addition, studies are aimed at optimizing controls of the engine and increasing the recirculation of exhaust gas, both of which are believed to result in high compression ratio and quite a boost in the mileage in vehicles.
Considering the gas mileage importance and availability in different fuels, there are numerous ways in which gas mileage can be improved. The most practical of all these ways is to drive less as possible. When it is necessary to drive, it will help to drive lightly. This means driving a small and light vehicle as possible and carrying lesser cargo. The lighter the vehicle you have, the faster you will drive. This way you can maximize your fuel use.
You can also cut your driving time by avoiding rush hours and major thoroughfares with high motorists concentration. Cutting your driving time does not mean, however, that you must drive fast. On the contrary, gas mileage goes down as driving speed goes up. As you increase you driving speed, much fuel is needed to cut through the air along your path. But don't drive too slow, either, because instantly increasing your speed uses much fuel. Remember to increase your speed smoothly.
Another way in which you can save up on those vehicle energy is by turning off the engine parking. When you plan to stay put for one minute and beyond, it is much better to turn off the engine. But if you plan to drive off immediately, it is much better to just keep the engine running. Frequent stop and start causes damage on the engine.
Since ethanol is making a noise in the fuel industry as a good alternative to gasoline and even diesel, consumers can also take into account a vehicle that can take flexible fuels. A flexible fuel vehicle enables an easier switch to ethanol or a combination of gasoline and ethanol, thus lessening the pollutants emitted into the air and making your ride as environmentally friendly as possible.