In 2 weeks I will have my very own black 08 #5 prius and I am so stoked, unfortunetly I am one of the many americans struggling with obesity. I am working on it and have lost 42 pounds hallelujah! And still going! But my concern is that with me and my wife in the car, the combined weight of the 2 of us totals to around 450 pounds. Now is this going to very heavily screw up my mpg number? Like I said I'm actively working on it, and am loosing a little more each week, but I'm really concerned that I'm going to get the same mpg as I did with my piece of sh*t jeep grand cherokee which is around 16mpg. Does anyone here carry or cart around about that much weight in their prius on a usual basis and see a significant effect on your mpg? Thanks!