[jetson]

Hillary the genious does not seem to understand that that technology applies to the pre 90's technology. The new cars have a different gearing to engine ratio so they can run at 2000 rpm at 75 miles an hour. The gas loss comes from city driving so the 55 number means nothing. What a dope.

[Prodn2000]

Actually. That is not true at all. At least IMHO. I drove to Alexandria LA from Dallas last Saturday in a 2007 V6 4D sedan. Averaged 34 MPG at 60 MPH and 27 at 75 MPG. I drove a hybrid V6 SUV and got 29 MPG at 60 MPH and 22-23 MPG at 75.

A pretty dramatic difference if you ask me.

[Melas]

Wrong. Extremely bad science. Fuel consumption at speed is a result of drag, not engine technology. While it's true that cars today use less gas at 70mph than previous generations of vehicles, today's most modern cars still use more fuel at 70 than at 80.

Drag is an exponential force. A car cruising on a highway at 50 mph (80 km/h) may require only 10 horsepower (7 kW) to overcome air drag, but that same car at 100 mph (160 km/h) requires 80 hp (60 kW). With a doubling of speed the drag (force) quadruples per the formula. Since power is the rate of doing work, exerting four times the force at twice the speed requires eight times the power. So, until they design an engine that uses less fuel while generating 40hp than it uses while generating 100hp (a physical impossibility) your statement is going to be absolutely false.