> because of Physics, an automatic transmission will always be less efficient

You making that claim based on how automatic transmissions currently work, right? And not on every way they could work.

Purely from logic, your claim has to be false: Imagine a humanoid robot sitting in your driver's seat, driving your manual transmission car, its robot arm doing the shifting exactly as a human would. Your manual car has been turned into an automatic and it is not less efficient.

I suppose you could argue that the robot, being part of the car, has an energy requirement. I would then argue that we could shrink the humanoid robot down to the size of chip with sensor inputs, and replace the robot arm and gear shift with a solenoid or whatever, thereby saving considerable energy.

By this thought experiment alone, I don't see how anyone can make a statement about automatics always being less efficient.