Tuesday, March 24, 2009

37 mpg in a 94 Corolla.

In these tight economic times, people want to save money wherever they can. I have managed to increase the fuel economy of my car about 5 percent: from about 34-35 mpg to 36-37 mpg. Here's what I've done.

(LEGAL DISCLAIMER: Always drive in a safe manner. Follow local driving laws and driving recommendations from your auto manufacturer. Your results may vary)

(Isn't it sad that we need discalimers? Oh well ...)

1) I increased my tire pressure. I picked a pressure about half-way between the recommended and the max tire pressure on the tire sidewall. This decreases the rolling resistance.

2) I drive 65 mph on the highway (occasionally 60). I realize that 65 is the law, but I just wanted to remind you that increasing your speed creates a huge amount of additional air resistance, and thus sucks the gallons of gas much faster. This is why during the gas shortage of the early 70's, the national speed limit was lowered to 55 - to save gas.

3) I turn off the engine if I am going to be sitting at stop light for more than about 30 sec. A friend in Finland tells me that it is the law over there to do this. This requires a knowledge of the route traveled, as some lights are fairly short, and probably not worth it, while others tend to be on the long side. Usually, unless I see the light turn red, I leave the engine on. TIP: If I'm driving a car with an automatic transmission, I slip it into "Neutral" when it is off. The car will start in either neutral or park, but neutral is closer to "Drive."

4) I skip gears. This doesn't apply to automatic transmissions. I have a manual transmission. The idea is to keep the engine speed as low as possible. I have found that driving around town, by the time I am ready to shift out of 3rd gear, I am pretty much going as fast as I want to be. Then I skip 4th and shift directly into 5th, since I just need to maintain my speed. I'm presently experimenting with skipping 3rd, i.e. shifting from 2nd to 4th and then on to 5th.

5) I coast. When I see a stop up ahead, I drop the car into neutral and coast. (WARNING: Do not do this with an automatic transmission. It is my understanding that it will ruin it. Instead, just take you foot off the gas.) The idea is that you don't continue pressing on the gas only to apply the brakes harder. (This idea save on brakes also.) In general, as soon as I see something up ahead, I coast. WARNING: ALWAYS leave the engine running. You need it for brakes and steering. Coasting with the engine off is illegal and dangerous! There are also a few hills that I can coast on, not so steep that the car is a runaway train, but enough to maintain the speed. You will learn where these places are on your regular commute. I estimate, that on my 15 mile commute, I probably coast between 1 and 2 miles.

There you have it. My hypermiling plan. It's about thinking about what you are doing when you drive: planning ahead; anticipating.

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