Mitsubishi has already shown us a PX-MiEV concept, and their second version is quite impressive in terms of fuel-efficiency. The PX-MiEV II concept returns an impressive 141mpg and features a hybrid powertrain. The hybrid powertrain consists of a 2.0-liter 4-cylinder engine along with two 60 kW (equivalent to 81hp) electric motors. When in EV mode, it can travel 31 miles and when the battery begins to be depleted, it automatically switches over to a Series Hybrid mode.