While surfing the net, I came across with a Japanese company called Aero Labo, which provides aero parts for various models. Among their products, "a-coro" is an aero kit for the current Toyota Prius (2nd gen)...which improves the fuel efficiency from 25.2km/l to 28.3km/l according to the company.
Source: Auto Labo
Source: Auto Labo
