The advantages of using increased levels in multilevel inverters?

The advantage of using inverters with more levels is that they produce a better approximation of a sine wave (lower harmonic content). An inverter with more levels is more efficient than an inverter with fewer levels and an output filter. However, an inverter with more levels has a higher manufacturing cost.

In the Tesla Roadster, there is apparently some battery utilization advantage that is gained by using a multilevel inverter with many low voltage batteries rather than just using a series / parallel array of batteries with fewer levels in the inverter.