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Gas Mileage – How to $ave

Gas Mileage

For years curiosity has kept me searching for the most economical way to drive. I have found that a variety of driving techniques work depending on the variables in vehicles. Obviously driving an RV differs from driving a car. RV’s take much longer to accelerate up to speed than cars. The power to weight ratio is the key factor. While RV’s typically have larger engines and more power than cars, the amount of horsepower to weight is much lower.

The key to obtaining maximum fuel economy is to keep the engine load as low as possible. There is a “sweet spot” or balance in every vehicles engine load to speed ratio. Contributing factors include: engine size, horsepower, torque, gear ratio, rolling resistance, and weight. Many newer automobiles have some type of an electronic fuel economy gauge in them. These units are very helpful in learning how to drive for fuel economy. In my opinion, one of the most incorrect pieces of information regarding fuel economy is in driving habits. I have heard many times “experts” advise slow starts and slow speeds are the best method of saving fuel. I disagree in most cases.
One of the misconceptions about economical driving pertains to fast or “jack rabbit” starts. Fuel economy numbers are directly related to engine load. Engine load is at or near its maximum during acceleration. While accelerating, the fuel economy is very low. Slow acceleration increase fuel economy very little if any. The difference between slow steady acceleration and fast acceleration in fuel economy numbers is very little. Once the vehicle is up to speed and cruising, the engine load is reduced and fuel economy numbers go up. In a set distance, the less accelerating and more light throttle cruising you do, the better the fuel economy. Get up to speed in as short a distance as possible. Yes, I’m telling you that quick “jack rabbit” starts are more economical. During a slow acceleration, fuel economy is very low all the way until the target speed is reached.

A we all know, stop and go driving reduces fuel economy. Any time a vehicle is sitting still, the fuel economy is 0 and as I just explained, during acceleration fuel economy is very low. Coasting with the throttle closed produces maximum fuel economy. There is a balance somewhere between accelerating and coasting. This balance is achieved when light throttle will maintain speed without accelerating.

Speed is one of the keys to achieving maximum fuel economy. Slow speed is not necessarily the best way to do it. Slows speeds in a high gear with high engine load is a recipe for poor fuel economy. The gear ratio and engine load are important factors in fuel economy. Maintaining the speed limit should be the goal in an RV. Getting your vehicle up to the speed limit and in its top gear in a short distance is important. Speed variations will occur on hills. Don’t try to maintain the speed limit on hills if wide open throttle must be used to do it.

Remember, using the least amount of fuel in a given distance is the goal. Using the top gear with light throttle will achieve the goal. Drive at constant steady speeds. Try to limit stop and go driving. Turn the engine off when not driving. Experiment with different fuel grades. Your vehicle constantly adjusts air/fuel mixture and ignition timing. Fuel octane grades act differently in some vehicles. Performance and fuel economy may be affected. It may be worth the extra cost for a higher grade. Be certain your engines air filter is clean and tires are at maximum recommended pressure. Be scientific when checking fuel economy. Fill the tank to the same level each time. The most accurate method for an accurate fuel economy test is to average every tank. Simply reset your trip meter at every fill up. Fill the tank each time and average all the numbers. You will have an accurate assessment of your vehicles fuel economy.

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