While each vehicle performs differently, a rule of thumb for maximizing fuel economy is to keep highway speed to 60 miles per hour or less. According to the Environmental Protection Agency (EPA), exceeding 60 miles per hour severely hurts the fuel economy of most vehicles. The agency says:
"each 5 miles per hour you drive over 60 miles per hour is like paying an additional $0.20 per gallon of gas."
Several tips on saving fuel appear at