Interesting, a car with an all electric propulsion system but equipped with only a tiny 1.5 KWH battery without a plug. Sort of like a Chevy Malibu Hybrid except the Malibu propulsion system is parallel hybrid where either the electric motor or the ICE, or both deliver power to the wheels. In the Nissan approach the drive motor has to be capable of delivering enough power to cover the entire performance envelop. In the Malibu the two motors are capable of propelling the car to maximum speed, but are not used that way since that would quickly depleat the battery. Instead, the motors are used to assist the ICE when torque demands are high such as launching from a stop or accelerating on to the freeway. This gives the Malibu V6 performance even though it has a smallish 4-cylinder ICE. However most of the time such as steady crusing the Malibu's power comes directly from the ICE (one of the electric motors in the Voltec transmission does use a small amount of power to provide variable gearing for the ICE).
Since both vehicles derive their power from the ICE most of the time, it seems to me a series hybrid approach, such as the Nissan would be less efficient then a parallel hybrid like the Malibu. In one (series) double losses are incurred when ICE mechanical power is converted to electricity which is then reconverted by the traction motor back to mechanical power to power the wheels. The I3 does this and even though it is a small car and its ICE is only 600 CC, the gas mileage is only around 38 MPG while the Malibu gets something around 46 MPG.
The 1st gen Volt was akso mostly series in its operation but it had a plug-in battery large enough to handle the majority of trips driven by an average driver. Unlike the 1st gen Volt, this Nissan hybrid with its tiny battery probably has to be powered from the ICE most of the time. Why do it using a series architecture when a good old fashioned mechanical drivetrain would be more efficient?