system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How a manual transmission car gets better gas mileage than an automatic.

So I'm about to get a manual car because I think it would be fun to learn to drive. And everyone keeps telling me that it's gonna be a little better on gas. I understand how cars work but I can't grasp why this would be true.
gpt
1. Weight - Manual transmissions are 30-50 lb lighter than automatics, so that's weight you don't have to accelerate or lug up a hill.


2. Transmission efficiency - Automatic transmissions require hydraulic pressure to work, so there are pumps inside, and some engine power is wasted to run those pumps.


Automatics are sometimes rated higher, but that's mostly because manufacturers have control over the shift points and they can tune them to work well in the EPA test cycle. With a manual transmission car, the test protocol dictates the shift points (unless there's a gear indicator). This puts manuals at a disadvantage as far as the test cycle goes, but a good driver will still do better with a manual transmission in the real world.


When manufacturers organize hypermiling contests or hire someone to drive across country using the least amount of fuel possible, they normally use manual transmission cars, even if the automatic does slightly better in the EPA cycle.