The myth: Manual transmissions are always more efficient than automatic transmissions.
The truth: In the old days, this was mostly true. Automatic transmissions back then were less sophisticated and often had fewer gears (typically three or four) than manual transmissions (normally four or five). Generally, the fewer the gears, the harder the engine has to work and so, the more fuel it consumes.
However, today’s automatic transmissions are a lot more efficient, thanks to electronic control and the use of modern materials to minimise power losses and reduce weight. Automatic transmissions also have more gears now. Many have six speeds; some have seven, eight or even nine, bettering manual transmissions which have largely peaked at six speeds.
Plus, advancements such as continuously-variable transmissions and dual-clutch transmissions have all but made manual transmissions a dying breed.