"Department of Energy, Argon
National Laboratory Study
Engine: 73%
more horsepower to cruise at 60 MPH., 159% more horsepower to cruise at
70 MPH.
Fuel Cost:
Research indicated that each mile per hour above 50 MPH increases fuel
consumption by 1.5%.
Tires: Tire
wear will almost double at road speeds of 70 MPH or greater.
Maintenance Cost:
Increasing from 60 MPH to 70 MPH increases the cost by 80%.