3 ms·
Cars with automatic transmissions (either planetary gear or dual-clutch) do often get better gas mileage than those with a traditional manual stick shift. The
by curlypaul924 8y ago
Cars with automatic transmissions (either planetary gear or dual-clutch) do often get better gas mileage than those with a traditional manual stick shift.
The reason is not what some might think. Once, a manual transmission was considered an economy feature. Cars with manual transmissions had a final drive ratio tuned for fuel economy.
Today, a manual transmission is considered a sporty feature. Cars with manual transmissions today are often tuned for performance, not economy. This can be seen in both the gear ratios of the transmission and how the engine is tuned. The result is a car that is zippier to drive, but less efficient.
- saltcured 8y agoIt's not just the final ratio. A modern automatic has a large number of closely-spaced gears and many of the engines have been tuned to have a very efficient low RPM cruise mode. Some have entirely different valve, injection, and ignition timing regimes for this low RPM cruise mode. It is very difficult for a human to keep the engine within such a narrow RPM band for efficiency, without accidentally lugging or stalling. So, they will likely spend their time with higher RPMs which miss these opportunities.
- benj111 8y agoI take it you would still need a human to get the very best fuel economy, just that its becoming increasing difficult to beat the automatic (like compilers v hand optimised ASM).
- astura 8y agoSince an automatic transmission costs more than a manual, any minor decrease in gas mileage is mostly a wash.
- analog31 8y agoIndeed, and driving habits (quality and quantity) play a much larger role in fuel cost.