Originally Posted by newyorker
Now I drive 60 and it feels like im going 40 because the engine keeps at lower rpm and its just quieter and smoother.
I'd say what's actually happened is that the speedo is stuffed. You probably actually are going 40 - that's the only thing that would explain lower revs.
Speed at the wheels = speed at the engine (ie rpm) x total gear ratios (or divided by, whichever way you look at it)
As you can see, this does not account for torque, power, fuel consumption, oil viscosity or anything - in fact, your engine doesn't even need to be running for this to hold true. As long as the drivetrain is engaged, if you can make your car move, then the rpm in a certain gear will ALWAYS be the same for a certain speed.