Mighty,
Auto-lean carbs were part of many WWII piston engines, and in the Bells that I flew back when men were men, but they were expensive and complex. Now cars use metered injection, with computers and sensors that were unheard of back then. These should be available in aircraft as soon as one engine manufacturer gets off his duff and does it - the savings in fuel alone will ake it an immediate winner in the marketplace.
I must say that the best leaning technique is to have a good digital EGT gage for each cylinder, and then you can lean whenever you wish.
Recall that very rich mixture is a way to assure slightly worse power but assured exhaust valve temperature, leaning to perhaps 50 degrees cooler than peak EGT assures peak power, and leaning to peak EGT yields best fuel consumption (although those who pay for the overhals often make it peak +25 degrees!)