Automobile fuel efficiency

Engine braking vs coasting

In my V6 1997 Passat GLX I found over the years that engine braking got me better mileage than idling during braking. When I started driving a 1999 Audi A4 with a smaller, turbo-charged engine, I found that idle sipped so little gas that it often was better to idle than to engine brake in it.

Now that I live in hilly Ithaca, with a 2007 Passat Wagon I have found that the choice of methods of braking depends on the speed and the slope of the hill.

In all these cases, the car has had a manual transmission, and I have used the on-board mileage computer to help with the studies.