At least with the waterboxer (and possibly other engines),  if you
are coasting, the engine managment goes pretty lean and you use very
little fuel.

Best gas mileage I ever got with my stock 2.1 Syncro Camper  was in
Colorado. In the morning we start east and headed up to Monarch Pass
(on US Route 50). I don't recall how far it was to the top. Not far
(50-75 miles or so). On the east side, it was leave it in gear and go
down the mountain. When I finally stopped for gas on the plains
(after about 320 miles total on the tank)  I end up getting around 20
mpg (and I sloshed some on the ground to be sure.)

On Apr 26, 2006, at 12:50 PM, monte merrick wrote:

> how does using the engine to slow down give better mileage than
> braking - i can see the safety angle, i can see the brake saving angle
> i live in mountainous terrain and recognize flatlanders immediately
> from their constantly glowing brakelights and the smell of cooking
> pads -
> i just don't understand the increased fuel efficiency - is it the
> use of energy already developed rather than just shedding that and
> then needing to build it all up again??
> thanks