Wednesday 23 August 2017
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Speed And Your Fuel Economy – Car Pro Commentary

As I write this article, Hurricane Isaac is centered over New Orleans, Louisiana. Oil drilling rigs in the Gulf coast region shut down yesterday for the safety of the workers, and gas prices jumped over ten cents per gallon overnight. We expected gas prices to jump heading in to the Labor Day weekend, but the hurricane made it even worse. I paid $4.39 per gallon in San Francisco less than a week ago and that was before the hurricane hit.
One question I get on the Car Pro Show often is, what can I do to better my fuel economy, short of trading for a new, fuel-efficient car? Of course, making sure your tire pressure is correct is a huge thing. Not carrying extra weight around in the vehicle, making sure the car is tuned properly, etc. We’ve all heard all the things we should do to better our gas mileage. The one thing most people do not realize is what a factor speed plays in your highway mileage.
I played around with some numbers that might surprise you. Before we get into dollars, let’s look at the time element of slowing down. If you average 75 miles per hour and slow down to 65 miles per hour, you will add 7 minutes per day to your drive, or 3 minutes and 30 seconds each way assuming a one hour drive. No matter what you drive, the time calculations above will not change. If you slow down from 75 to 60 miles per hour, the time added is 5 minutes 30 seconds each way.
Looking at the dollars in the scenario above, I based my calculations on $4 per gallon gas, using a vehicle that gets 25 miles per gallon on the highway, and 20,000 miles per year. If you normally drive 75 miles per hour, your annual fuel cost is $4164. By slowing down to 65 miles per hour, you cut your fuel cost to $3493. 10 miles per hour will result in a savings of $671. If you slow down to 60, the savings go to $858. If you are a real speedster and drive 80 normally, dropping down to 60 miles per hour saves you almost $100 per month.
In a different scenario of gas dropping to $3 per gallon and a driver only traveling 15,000 miles per year in a 35 mile per gallon highway vehicle, slowing from 75 to 60 miles per hour results in a savings of $340 per year, nothing to sneeze at.
A couple of reasons for the decrease in fuel economy are that most vehicles today are set to run at the most fuel-efficient at speeds of 55 to 60 miles per hour. Once you go faster, the vehicle gets much less fuel-efficient. The other big reason is just wind resistance. The faster you go, the harder the car has to work to get through the wind.
Lastly, consider how much safer it is if you slow down. At higher speeds, your reactions are more pronounced and dangerous, and your stopping distance increases greatly. Even the major airlines have figured this out. Southwest Airlines have slowed their planes down an average of 10 miles per hour. This only added 3-4 minutes to each flight and has saved them over forty million dollars annually.
Whether for saving money, being mindful of safety, or avoiding costly speeding tickets, slowing down just makes sense.

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