Sunday, May 25, 2008

Three Laws of Car Fuel Economy

Okay, the price of car fuel is going through the roof. What are we going to do about it? Drive less?--That's a very good way to stop global warming. Not a good way to be at Aunt Martha's picnic this weekend.

We could get a super-efficient car (like mine--gets 65 mpg) or get a super-efficient engine (like the one under development--see the full theory at, but you would probably miss the picnic. How about some ways to really cut the cost of gasoline TODAY?

That brings me to a new set of rules. You might say they are Rogers' Laws of Car Fuel Economy. These were mostly known before. They may not actually work for everybody's car, depending on how the car was engineered. A well-engineered car should follow the rules to a "T."

Here are the rules. By following them, you should be able to cut your fuel costs by 20% or more, starting today!

Three Laws of Car Fuel Economy
Ernest Rogers May, 2008

1. In highway driving, for each 5 mph that you slow down, your mileage will increase by 10%.

2. For any trip with a present average speed of (mph) and fuel consumption of (mpg), if you speed up to save time, the extra fuel you will use can be estimated by—

Extra gallons = (mph /mpg) x (minutes saved /35)

In words, if you divide your normal speed by your usual mpg, then multiply by minutes you want to save (by speeding up) and divide by 35, that’s the amount of extra fuel you can expect to use. It is a handy rule to see the fuel cost for speeding to save time.

3. Very efficient drivers use pedals less and can get 30% better mileage than inefficient drivers.