How does an automatic transmission get better gas mileage than a manual?

I've been noticing that on a lot of new cars, the four speed automatic transmissions are labeled as having better gas mileage than standard transmissions. Stick shifts have always been known to provide better mileage and performance.|||Technology is getting better for the automatic transmission, but new specs are supposed to be more true world for mileage expectations. The truth is, a lot of people really don't know how to drive a stick for economy, they think stick is for better performance. You can't have your cake and eat it too. Give me 2 cars, one auto, one stick, with the same number of speeds, and same final drive ratio, and I can get fractionally better mileage out of the stick every time, by driving for economy. However, if you have a 4-speed stick, and a 5 or 6-speed auto, the auto will do better. Sometimes, comparing the stick to the auto is like comparing apples to oranges.|||I've wondered a bit about driving up a hill with an (underpowered/loaded) Auto Transmission vs Manual Transmission.





Manual Transmission-Driver adjusts speed%26amp;power with gear, downshifts when needed.


Auto Transmission-Tranny fights to maintain speed, downshifts at unexpected times.





Efficiency?

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|||That's not true. Automatic tranny gets about 10% hotter. So that heat (energy) has to come from somewhere.





The only exception might be (MIGHT) are some "automatic" tranny with REAL clutch (new Mustangs). Then they are really manual with computer controlled clutch. Then the computer can be programmed to shift at the most efficient point.





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But that is NOT to say that in REAL life (not factory estimate), that a manual car will always get better MPG than a auto. Most people who shift late will most likely get worse MPG than in an auto.





But I think you were asking about the FACTORY ESTIMATE.








Good Luck...|||Technology is just getting better. Autos used to be 3 speeds or maybe 4 speeds. Having fewer forward gears meant having to accelerate more before being able to shift into the next gear. But now with 5 and 6 speeds becoming common, coupled with smoother faster shifting, they are able to get better mileage.|||The standards use backpressure that helps to slow down, but the automatics freewheel when you let of the gas, sort of like putting it in neutral and coasting...plus they use big overdrive ratios..