Just bought it used. Carfax showed clean, no issues, no accidents, regular maintenance, 126k miles. I didn't take it out on a highway test before buying and am only now realizing that it has a serious problem. MPG is only 27 and it can barely make it up hills. Even S gear is lame gear. I figure that the car's battery, now more than 10 years old, must have significantly diminished capacity. I'm taking it to a dealership Monday to get it looked at, but I'm prepared for the inevitable. I've heard of Priuses getting amazing mileage on original batteries... what is it with Hondas? Why do their batteries die early? Assuming I can't get a replacement because I live in Ohio and warranty is out (and the IMA light isn't on), I figure I'm looking at getting a new battery. I see offerings for original rated batteries with 6.5ah and higher rated ones with 8ah. Has there been any real testing to estimate the lifetime of these batteries?