sentences:  In September, the California Cars Initiative converted a 2004 Toyota Prius into a prototype of what it calls the PRIUS+.With the addition of 130 kg (300 lb) of lead-acid batteries, the PRIUS+ achieved roughly double the gasoline mileage of a standard Prius and can make trips of up to using only electric power.The vehicle, which is owned by CalCars technical lead Ron Gremban, is used in daily driving, as well as a test bed for various improvements to the system.