Today while I was roading the backhoe around town I had a thought- Does an engine always use the same amount of fuel at a certain RPM? If you rev your motor up to 2000 RPMs at idle, will the motor go through the same amount of fuel as it will cruising down the highway at 2000 RPMs? I know that in idle the motor doesn't have to transfer power through the drivetrain, but at speed the truck has momentum which *MAY* help with fuel consumption. So is there an advantage either way? I also know that you have to take load and throttle position into consideration, so I'm just talking about idle vs. cruising speed. Anyhow, I hope my question makes sense. I know there are many variables that could affect the actual outcome, but in theory, does anyone know if there's a difference? To me, 2000 RPMs should use the same amount of fuel either way.