Cars heading east on Highway 10 near Marshfield, Tuesday, August 20, 2013. The state Assembly is proposing a bill that would increase the speed limit to 70 mph.
EDITOR: Especially when our elected officials should be looking for ways to reduce our greenhouse-gas emissions, it makes little sense to raise speed limits. Data from the Department of Energy show that compared to the 55 mph speed at which vehicle fuel economy is calculated, the average vehicle will be only 3 percent less efficient at 60 mph, but 8 percent less efficient at 65 mph and a whopping 17 percent less efficient at 70 mph.
Some back-of-the-envelope calculations, based on a roundtrip from Stevens Point to Madison, show the following: Total mileage is about 225 miles. Driving at 70 mph compared to 65 mph reduces fuel efficiency by 9 percent on average. Assuming 25 miles per gallon at 55 mph, 10.4 gallons of fuel will be used at 65 mph and 11.56 gallons at 70 mph. At $3.65 per gallon, the faster speed costs an additional $4.23.
Time saved by driving faster is a bit less than eight minutes each way, or a total of 15 minutes for the roundtrip.
There probably are some days when one might need to sacrifice $4.23 to save 15 minutes, but we'd all be better off if we slow down, be safer, reduce our carbon footprint and save a few bucks.
Alan W. Haney,