OK, I spent today driving from Atlanta to the St. Louis area. Just me and a rented Ford Tarus (blech). Anyway, I'd rather drive than fly, and a nice drive it was. As I crossed into Illinois, though, I was playing with the onboard computer, and came across the MPG calculator. I was able to determine that I was getting about 26.5 MPG at the 80+mph I was cruising (shhhhhh, don't tell). With the current high gas prices, I wondered just how wasteful I waqs being. When I got onto Rt4, I had an opportunity for a ~20mile run at 60 mph. That 25% decrease in speed jumped the milage up to 30.2 MPG (yes, I reset the meter!). OK, a 25% reduction in speed leads to a 14% increase in gas milage. Sounds pretty good. But what would that mean, in real dollars, over the course of my day?? The trip was right at 600 miles, if I drove the whole thing at 80, that would be 22.6 gallons. At 60mph, it would only take 19.9 gallons. SO, a reduction in speed would've saved 2.8 gallons. At $2.80/gallon, thats a savings of $7.77.
On the other hand, at 80mph, the trip would take 7.5 hours, versus 10 hrs at 60mph.
In summary.... For 2.5 hours of my time, I could've saved less than $8.00 of gas. Ummm, not gonna happen.