Well automatics take a whole different approach,, I did some testing in the sable.
I used a 4 mile stretch with a 55 mph speed.
I drove 2 miles stopped turned around and came back 2 miles.
I don't have a bunch of individual numbers for ya, but it goes like this.
Full throttle.. runs were between 28 and 29 mpg
granny style were 31 to 32 mpg
The best was moderate throttle up to 35 mph where it shifts to OD then very slow accel to 55. This netted 34 to 35 mpg range.
This wasn't a surprise to me, thats how I normally drive.
The problem with a auto is you can't short shift it to stay at lower rpms.
For example, a full throttle run in the sable is ... 1st gear up to 45 mph 6200 rpms.... then to second gear up to 77 mph 6200 rpms. This engine won't shift at WOT until it hits the rev limiter at around 6200 rpm, trying to shift it manually does not help.