I just got a 4Kwh Enginer kit installed on my 2007 Prius. This is the only mod for the car - not even a Scangague (wife thinks it's ugly). I haven't taken any 'hard' numbers yet or made any charts. I'm an odd user - this is my ONLY car for a family of four, and two drivers, so this system will get a workout. First impressions are that it basically works as advertised. In the city if I use EV mode a lot, I can get close to infinity MPG, but the battery will go dead fairly quickly (under 20 miles). I noticed that if I go a full 5 min on EV, consuming no gas, the consumption bar reads zero instead of 99.9. I assume this is because the computer is trying to divide by zero. In blended mode, I can get 80MPG+ at 60MPH+ if I drive right - basically get up to speed, let go of the gas, and lean on slowly to get slow RPMs and maintain speed. Amazing how quiet and smooth it is driving this way - almost like gliding in a pluse/glide over 50MPH with the 'all yellow' arrows. Range seems to be a little less than advertised. Haven't taken hard numbers. I would say 30-35 blended and 12-15 EV. I might get more as I learn to drive it more efficiently. The EV switch that comes with the unit is not so great. - If you turn on the Enginer, it turns on EV automatically, even if you don't want it to. Then, you have to figure out how to shut it off (jam gas, go over 34, hit defogger...) - If you shut off the Enginer, it does not shut off EV. - If the Enginer is on, there is no way to turn on EV. You have to flip off, then on again, but it's risky. - If the Enginer system is dead and you use the switch to enter EV, the Enginer will come on and it will take a little while until it detects that the batteries are low. During the wait, it may be overdraining the batteries (not sure about this). Installation was done my Motor City Motors in Troy, MI at the Enginer facility. It went well - they installed it in about two hours and I drove home. They even let me watch and take a video/pictures, although I had to promise to stay out of the tech's way and not ask questions (they charge extra for installation training).