I wondered why the EPA's figures for the gas mileage on the 6 speed auto didn't improve over the 5 speed autos?
The "5 speed" (545rfe) and "6 speed" (65rfe) are the same transmission. Both have 6 forward gears and skip the 3rd gear on normal upshifts in drive. It was renamed for marketing.
The 8 speed has the exact same final gear ratio as the 545rfe/65rfe.