Monday, August 4, 2008

Reducing Gas Cost by Improving Mileage

One of the largest single energy expenses for a family is gasoline. With the price of gasoline getting so much attention, many people are wandering what to do to improve their fuel economy and thus reduce fuel cost on a monthly and annual basis. The driving suggestions indicated here have all been tried by the author with an easy 15-20% improvement in fuel economy. For this author, that's an extra 100 miles per tank. The bottom line to improving fuel economy is simple: the engine is there to propel the car. Let it do its job. Keep the car moving, maintain momentum and reduce stops and idling.

1. Reduce the weight in the car. Every extra pound carried in the car and trunk is extra work for the engine. It's also a momentum sponge, draining momentum every time the accelerator is released.

2. Maximize tire pressure. Run the tires to at least the car manufacturer's maximum pressure rating. Some advocates recommend going beyond the car manufacturer's maximum rating and going instead to the tire manufacturer's maximum rating. Check with your auto mechanic for is advice on this.

3. SLOOOOOW down on the acceleration. Slow WAY down. Accelerations are the hardest work for the engine. Keep engine RPM's low (below 2000) at all times, especially during acceleration.

4. Minimize decelerations. Watch out for stop lights. If they are red or about turn red, let off and coast as far back as possible. No need to fly up to the light and slam on the brakes. The best solution is to hit the light just as it turns green to maintain at least some momentum. Some advocates recommend a sharp reduction in speed far back from the light and slowing coasting forward. This will adjust your timing so you can continue to roll slowly up to the light as it turns green.

5. Minimize left-hand turns. Left hand turns mean potential waiting on oncoming traffic. Remember, we want to keep moving, not waiting.

6. Keep engine RPM's down to 2000 or less at all times. For modern overdrive cars, this usually means 61-64 MPH maximum. For older cars this could be as little as 55 MPH. This is critical and causes the most reason for objection. Most of us are used to getting there as quickly as possible. Watching RPM's This forces us to slow down.

7. Investigate an instantaneous miles per gallon (MPG) computer. Some cars have this available on their on-board computer. If not these MPG Computers will plug into your car's engine control computer. This allows you to constantly monitor your driving conditions and make adjustments to speed or acceleration accordingly.

8. Let gravity help. If you are currently going at the speed limit, let off the gas (or press in the clutch on a manual shift) when going down hills. If you are going below the speed limit, keep the 2000 RPM engine speed and gain speed when going down the hill in preparation for the next uphill climb.

9. When going uphill, watch the engine RPM's. This may even result in a reduction in speed up the hill to maintain the sacred 2000 RPM limit.

10.Keep the windows up! For speeds over about 45, having the windows down actually causes as much or more drag on the car than running the air conditioning. For lower speeds such as city driving rolling the windows down is better. The best solution of all on moderate days is windows up, fan on, AC off.

11. Use synthetic oil if your car manufacturer recommends it. Synthetic oil has much less friction and allow the engine (or transmission if changed) to operate much efficiently with less drag.

12. Combine trips. A hot engine is more efficient than a cold engine because of extra friction from the cold oil. Combining trips keeps the engine hot. In general 1 ten mile trip is much more efficient that 2 five mile trips.

There is a group of enthusiast called hypermilers. Hypermiling is taking the fuel economy of your car to the extreme. Where this author has easily obtained 15-20% improvement, some hypermilers claim to have doubled their mileage. There are numerous sites showing advanced hypermiling tips and driving techniques.

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