180 MPG!

A modified Prius is claimed to get 120-180 according to a report in EV World.  EnergyCS modified the Prius by installing their battery monitoring system, replacing the cars 1.3 kWh NiMH batteries with 9 kWh Valance Saphion phosphate based Lithium Ion batteries and an on-board charging system.  By plugging in and recharging the batteries overnight the car is able to to get 120-180 mpg for the first 50-60 miles of travel, until the batteries are nearly discharged. Then the average mileage drops back to about 50 mpg in the normal Prius operating mode.  The higher mileage is possible because 9kWh of electricity was taken off the grid to charge the batteries. Not really any net energy saved, but the saving in gasoline and reduced emissions along the driving route are significant.  The batteries have one-third the weight, twice the run time, faster recharge rate and higher cycle life then lead acid batteries.  According to a NY Times article the modification to the car would add $2,000 to $3,000 to the cars price.