One-pedal driving
A driving mode where lifting off the accelerator slows the car strongly through regenerative braking. Some cars bring themselves to a complete stop this way.
One-pedal driving takes regenerative braking to its strongest setting: press the accelerator to go, ease off to slow. The deceleration is strong enough that in some traffic you may not need the brake pedal, and some implementations regenerate all the way to a standstill and hold the car there.
Whether it suits you is a matter of preference. Some cars that offer the mode let you reduce the regen strength or turn it off, and some remember your choice per drive mode.
Implementations differ in ways a test drive shows quickly: whether the car stops completely or creeps, how adjustable the strength is, and how the car signals strong regen deceleration to drivers behind.
On efficiency, fueleconomy.gov advises anticipating stops and braking gently so that the regenerative system can recover energy, since hard braking uses the conventional friction brakes, which do not recover energy. How much one-pedal mode changes your own efficiency depends on how you drive.