Earlier quoted context omitted.
The biggest disadvantage autos still have versus manuals is their larger size and higher parasitic power loss. Americans tend to drive both larger and more powerful cars where the drawbacks of the auto over the manual are pretty much insignificant. Smaller European cars with lower power figures have more difficulty physically fitting the automatic transmission and the power loss from the torque converter is more noti…
I'm a car noob, but how is physically fitting automation into a device difficult? Isn't it a tiny chip on a board?
Manual transmissions typically consist mainly of a locking mechanism that is physically moved with the shifter for gear selection and a clutch plate to couple the transmission to the engine. Typically you have one physical gear for every logical gear, and you're using the shifter to physically connect to the gear you want to use. The clutch plate is a friction material, and you press it against the flywheel (which connects to the engine) for them to stick together; press them together and the engine spins the transmission, pull them apart and you're in neutral.
In your typical automatic transmission, instead of having a physical gear for every logical gear, you have multiple sets of planetary gearsets (typically 3 sets for a 6 speed). Each planetary gearset has its own clutch to allow different parts of the planetary gearset to spin, allowing for multiple different ratios. The computer controls which clutches are applied to make the right ratio for the "gear" you're in. A torque converter is used to connect an automatic transmission to the engine instead of a clutch. Torque converters are two fans facing each other submerged in liquid, when one fan spins, it moves the liquid which spins the other fan.
Planetary gearsets of the auto transmission are typically bigger than simple gears, and the torque convertor with two fans and liquid is significantly bigger than a clutch plate which is just a flat disk.
Now you're thinking, why can't a computer just control the clutch plate movement. Well, BMW tried it with their SMG gearbox. Turns out computers aren't very good at determining how much force to apply to the clutch (which also wears over time) so that the car doesn't jerk or lag, much less figure out whether you wanted aggressive clutch engagement or you wanted the clutch to slip. Compared to letting physics do it's thing in a torque converter, a computer controlling a moving part was also much more complicated and less reliable and less predictable. The computer is already not very good at predicting what gear you want to be in, it was also not good at predicting how direct you wanted your power applied. So it ended up being worst of both worlds, none of the simplicity of a true manual, and none of the smoothness of a typical auto.