This question already has an answer here:
- How does a clutch work? 2 answers
When a manual transmission car is stopped on level ground, it is possible (for some cars) to make it start moving without using the gas pedal by putting it in gear and bringing the clutch to the friction point. If the clutch pedal is fully released, this acceleration will cease, causing the car to stall if it has not gathered enough momentum.
Why does this happen? What causes the car to accelerate when the clutch is in the friction zone but not when it is fully in gear?
Note that I already asked this, but that question was closed because people didn't understand it.