The EPA says that "each 5 mph you drive over 60 mph is like paying an additional $0.20 per gallon for gas".
I like to do arithmetic around here. It keeps me from being stupid. Here goes.
Suppose you need to drive 780 miles. You can do that two ways:
- 13 hours @ 60 MPH, or
- 12 hours @ 65 MPH
Further suppose that you get 20 miles to the gallon at 60 MPH, for a total of 39 gallons used.
The EPA says you are losing 20 cents for each of those gallons, for a total of $7.80 over the course of the trip.
Is an hour of your time worth more than $7.80? If so, you should drive at 65 not 60.
The math here implies that it is $7.80 for each 5 miles per hour over the speed limit. In my case, I make about $60 per hour on my main job. So, I should drive about 120 when other people are driving 60. Autobahn anyone?
I don't drive that fast. I have other reasons - like safety - for this.
But, don't get this wrong: I'm already choosing to save gas from what is optimal for me given the EPA's own metric.
What exactly do you call someone who nags you to do what you're already doing because it is "good".
Puritan, that's what.