Back in January '09, I remember reading a review of Hymotion from Consumer Reports Magazine. There was one thing that I remember reading in that article, and still question. CU claimed that in their tests that when the Hymotion had depleted its charge, their Test Prius mileage was an average of 2 mpg worse than it would be if the car did not have Hymotion, and had a whopping 5-mpg loss in city driving! They claimed that the 200 pound of extra equipment was the cause. Anyone know if that is true? If you carry a 200 pound passenger, instead of driving alone, do you lose that much mpg in a standard Prius? From CU Article: "We could usually drive an average of 35 miles before the new battery was depleted; unlike the original battery, it can't be charged by the gas engine. After that, the plug-in Prius returns to its normal operation. But the extra weight of the new battery drops its gas mileage from 42 to 40 mpg overall and from 34 to 29 mpg in the city."
A 2 mpg overall drop isn't that big. Please go through the calculations mentioned at http://priuschat.com/forums/other-c...eage-no-its-your-gallonage-really-counts.html. People like TheForce thru dedication, hacks, patience and ideal commute have gotten numbers like 2502 Miles 299 MPG 1 tank of gas in a 2G Prius PHEV | PriusChat.
I have not observed any mileage hit when driving with an empty pack. I would say that obviously for every X pounds of weight you add to any car, your MPGs will drop Y percent, but it has not been perceivable to me.
