Each day at the end of my commute to work from the Outer Banks to VA I reach the following decision point in the trip. At the NC/VA line I can..
..take the Highway almost all the way to work; 14 min, 12.6 mi, speeds 60-70 miles per hour @~48 mpg.
..take the Highway 50% and local streets 50%; 15 min, 11.5 mi, speeds 60-70 Hwy and 30-40 local, @ 48 mpg & 60 mpg.
..take only local roads with 11 lights; 17 min, 12.1 mi, speeds 30-40 miles per hour @ 60-70 mpg

Based on the averages, for 240 annual trips the annual fuel used would be...
Highway: longest distance, shortest time, most fuel used @ 62.4 gal
Hwy/Local: shortest distance, 1 min longer trip, fuel used @ 51.1 gal
All Local: 0.5 mi longer trip, 3 min longer trip, fuel used @ 46.7 gal

Why don't the hybrids get the EPA fuel economy ratings that they advertise? Because the drivers choose not to optimize the vehicle's fuel economy in favor of other considerations, ease of trip, time constraints, inertia.

YEAAAAA!!!! YEAAAAAA!!!! YEASSSS!!

Exactly! Choose the route that accomplishes your goals and life is good.

Bob Wilson

Operation Iraqi Oil Freedom:

Automatic, stock, project car.

My other 1500 cc car:

Automatic, stock, backup car.
Free speech, dialog and knowledge thrives without the poison of SPAM.

Hey which do you usually choose? Why not plan D - cruise on the HWY at below 60mph (if you can) - takes more time, but helps mpg and less stops.

Going to work I choose Door #2..
By chance today I remeasured the values using the MFD.
Hwy 6.0 mi @ 65 miles per hour gave a readout of 55.4 mpg ( I was surprised )
City 5.5 mi @ 30+ miles per hour gave a readout of 65+ mpg ( not so surprised )

Coming from work I always opt for #3

I try to avoid the Hwy as much as possible without being ridiculous about it.

I do exactly the same.

Alden Bowles
2005 Toyota Prius II HSD