Continuously Variable transmissions (CVTs) may not be the most exciting transmissions, but they are efficient. According to Jason Fenske of Engineering Explained, however, there is a time where having an actual gear is superior efficiency-wise to a belt-driven cone: Accelerating from a stop.
Toyota recently implemented this theory into its latest CVT, installing a first gear for accelerating from a stop. You see, at very low speeds, the transmission belt is at the extreme end of its spectrum, asking for lots of torque at a very low gear. This positions the belt at a narrow end of the cone, which is its most inefficient point. Inefficiency is bad, so Toyota added a gear to substitute.
And because the CVT no longer has to worry about accelerating the car from a stop, both cones can be smaller and have fewer parts, which means a lighter, less complex system. Fenske explains it all, along with some other benefits of adding a first gear to a CVT, in his latest video below.