Why are cars with manual transmissions sometimes more fuel efficient than cars with automatic transmissions?

Mudassir Ali
Feb 15, 2020 05:02 AM 0 Answers
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Mudassir Ali
- Feb 15, 2020 05:02 AM

Originally Answered: Why does manual transmission consume fuel more efficiently than automatic transmission?
Automatic transmission cars get less fuel efficiency because:

1. They weigh more.

2. The torque converter is a fluid coupling that allows some slippage while the engine slows to the lower RPM on an upshift or a higher RPM on a downshift. That slippage is inefficient (turns power to heat).

Modern automatics have a torque converter lockup that locks the slippage once the gear is shifted and the engine settled to its new speed, so the loss is less severe than older models where there was always slippage.

Many automatics don’t engage the torque converter lockup in low gears or when the transmission is not warmed up.

3. The shifting program doesn’t have a knowledge of drivers intent; a manual driver can upshift sooner at top of a hill or end of acceleration, and downshift sooner (with less “kick-down” use of gas) on an uphill or passing move.

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