I suspect that in the Kicks’ case, “L” was renamed “B” for a few reasons. Technically, you’re not selecting a lower gear because
CVTs don’t have gears (well,
most of them anyway); rather, the “B” mode effectively simulates a low gear ratio, allowing for engine braking when off throttle. This may burn more fuel but, at least when cruising downhill, should keep you from riding that brake pedal. Additionally, Nissan might’ve settled on the “B” name to create surface-level consistency with its EVs, which have similarly laid-out shifters.