While you’re usually not supposed to touch the shifter of an automatic transmission while you’re in motion, the “L” or “1” setting is usually located right next to the “D” setting, so you can activate it without any excessive or dangerous shifting. To do so, just ease off the gas pedal to a slow speed, shift the selector to the side the L is on, and it’ll activate automatically.
The low gear setting, as the name implies, forces your transmission to basically stay on the lower settings. This is accomplished by restricting the amount of fuel flowing from the intake into your engine. This, in turn, reduces your car’s overall speed.
Why would you want to do that? Because when the gear is restricted, your car is capable of exerting more torque. Basically, when you shift into low gear, your car gets slower, but it also gets much stronger, capable of exerting more pounds of forward force, which can be especially helpful in specific vehicle scenarios, or even emergency situations.