ANSWERS: 8
  • There are several reasons, but the main factor is weight. Automatic transmissions, for all their benefits, are much heavier than manual transmissions. Less weight to move = less gas needed to move the vehicle. Also, depending on the driver, shifting habits can allow for better mileage with a stick. You can shift hard and fast for power, or nice and slow for mileage. An automatic transmission doesn't know what you are planning to do - pass, coast, etc. Only the driver knows. So, it may hold a gear for longer than needed and waste fuel. However, with a manual the driver can shift up or just put the clutch in (both bring the rpms down) and therefore save fuel. I like stick because most automatics feel dead to me. They take the fun out of the car.
  • 1) Clutches provide a direct mechanical connection while torque converters are a fluid coupling with less than 100% efficiency... BEFORE getting to the transmission. 2) Though less true now than in years past, automatics have fewer and more widely-spaced gears.
  • Simply because in a manual transmission car, you have a direct mechanical link to your drivewheels. In an automatic transmission you have what's called a "fluid coupling" which is like placing one fan in front of another then turning one on and seeing the wind from it turn the blades of the other fan. There's always going to be some slippage in an automatic transmission; even the more complcated ones with a lockup clutch device that tries to correct the slippage problem of fluid coupling. Also an automatic transmission is the most complicated part of a car. A labarynth of channels valves and band drives. As it goes so goes the car. In a manual transmission it's far less complex. Less complexity means also a lighter transmission. It's also far easier to service or even replace, if needed. To save even more fuel in my manual transmission car I can do what's called "short-shifting" which is not reving the engine anywhere near the redline before shifting. By doing this I turn fewer RPM and that means increased gas mileage.
  • Some of the newer Auto's with overdrive and lock-up clutches (generally 4 speed) can actually be more fuel efficient in the right conditions (easy highway cruising) than a manual shift.
  • Plenty of reasons, though I disagree that weight is the main reason. The spacing of the gear ratios is also important, but secondary. To me, the main reason is control. I get 48+ miles per gallon out of a bone-stock manual transmission Corolla because the manual permits me to alter my driving habits a lot more than I could with an automatic.
  • Energy is wasted in the form of heat in the torque converter. Its like a turbine blade that blows oil onto another turbine blade. The heat is cooled in the radiator. Manual transmissions have a friction clutch, no energy wasted.
  • because the clutch on a manual trans is always transfering full engine power to the wheels where in an automatic it has a torque converter which doesnt do this it wastes about ten percent of the engines powerand the other guy who said that the torque converter is less than 100% efficient is f-in stupid if somethin is less than 100% than you wouldnt be moving now would you trust me this is the number one answer
  • Will in my opinion it's not all about the type of transmission there are some effect. Like final drive gear ratios,the number of gears in the transmission,driver shift patterns and even vehical weigth (automatic are heavier) all play an important part in fuel economy.

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