Posted by DBLZOOM on July 12, 2006, 11:30 am
As far as highway driving is concerned, I have found with my 2001
Classic Prius that it does not matter if I'm going 65 or 75, I still
get 51 mpg even with the air conditioning on. I travel from Cleveland
to Detroit quite often and couldn't believe that I would get better gas
mileage at the higher highway speed. From what I have heard, the Prius
engine is the most efficient when running around 4000-4500 RPM. I
believe that running in this high efficiency range is what is causing
my gas mileage to be good at higher speeds. I get worse mileage in
town whne I am driving slow.
I don't have anything against driving the speed limit, especially in
construction zones but I think there are some physics involved here and
just driving slow doesn't mean you are automatically going to get
better gas mileage.
Posted by Bill on July 12, 2006, 3:41 pm
Yes, some physics are involved, but the optimum speed to maximize mileage is
below 41 mph. On the open road, our mileage varies greatly depending on
wind velocity and direction. Driving 75 mph with a 30 mph tailwind will
yield mileage roughly equivalent to driving 45 mph with no tailwind.
Driving 55 mph with a 30 mph headwind sucks. Where I live the winds are
such a significant factor as to effect the mileage calculation on most
highway trips. Ask a pilot.
Posted by Michelle Steiner on July 12, 2006, 6:26 pm
I also discovered that at speeds under 40 MPH, driving with the windows
open and the A/C off gets better mileage than driving with the A/C on
and windows closed.
Faster than 40, though, keep the windows closed and the A/C on if you
Stop Mad Cowboy Disease: Impeach the son of a Bush.
Posted by Bob Wilson on July 13, 2006, 8:28 am
My results are different as far as MPH vs. MPG is concerned:
As for AC, I find that above 50 mph, it is about a 3-4 MPG hit. At
temperatures up to 90F, I can usually get by with windows and wind.
Above 90F, it has to be dry and not have direct sunlight. Otherwise, the
AC works just fine.
Now when my wife is with me, the AC comes on right away.