I just upgraded my 2010 Prius to the NexPower Nexcell upgrade Installation was simple. Nothing too tricky. I think the 6.6Ah rating is wrong, it should be double because it takes up twice the space as the regular blades. 1. My gas mileage when up from 40 mpg back to stock new 50 mpg. I think if you have a typical drive, the benefit can only come from these batteries don't get as hot as the Nimh. Less heat means more energy is stored. Or it might be the way the sensor is hooked up. it's mounted horizontally, which might make these batteries seem to operate cooler. In any case as far as Gas Mileage for me it brings it back to new OEM levels. 2. EV range. I conducted an unscientific test, and EV range from battery level NOT FULL 60% (bars not on in the battery) engine when on that 45%. I traveled a total of 1.7 miles. I search and consensus is OEM battery at full (~80%) has a range of 1.1 miles. This battery at 60% had .6 miles more range. I guess the capacity is roughly double the OEM pack. Given the capacity, if your drive has a large uphill and downhill approx 1-2 miles long you can have a benefit of greater gas mileage. I'm not sure how you would tell it to discharge on the way up, and regen on the way down. Anyways that's my review.