Why do you think it unlikely an automatic can match or exceed a manual in fuel economy? Computers can better fit the torque needs to the most efficient RPM than most humans will, it's not a hard problem to solve.
Traditionally (and this is from the very olden days) manuals had an extra gear over automatics, which is why they'd have better fuel economy. Also less drivetrain loss. Nowadays the reverse is true, automatics consistently have more gears to play with, and automatic clutch packs are fantastically fast & good.
Now an efficient automatic is more complicated to design & manufactur, but that's where economies of scale and advancements in engineering tools and manufacturing come into play
Traditionally (and this is from the very olden days) manuals had an extra gear over automatics, which is why they'd have better fuel economy. Also less drivetrain loss. Nowadays the reverse is true, automatics consistently have more gears to play with, and automatic clutch packs are fantastically fast & good.
Now an efficient automatic is more complicated to design & manufactur, but that's where economies of scale and advancements in engineering tools and manufacturing come into play