[donee]

Hi Big Dave and MetroMPG,

There is a guy named Ernie Rogers who has modified his TDI Beetle. And claims to gain much improvement at highway speed. And after been in a Beetle recently at 45 mph, I can sure believe what he has done will have some effect. The roar of sheer vorticies to the outside of the car, right about the rear passenger head level is horrendous.

Of course diesels do not have throttles. So, while without gearing changes, there is no pumping loss improvement. The part throttle performance of diesels is very good, however. And when one lifts up on the accellerator, less fuel is injected. When less force is needed to push the car, its an imediate response that less fuel need be injected to keep the engine at the speed.

Reducing the pumping losses is probably why the diesel CVT Partnership for a Next Generation Vehicles (PNGV) were up around 70 to 80 EPA mpg. They could reduce fuel injection quantity, besides the number of times a second that quantity was injected.