My civic is 8 years old and when I noticed the mileage was just not as goo,d I took it to the dealer. $3100 for a new battery. It is running fine and will do so until I get another car. Not worth replacing it. Won't buy a hybrid again and I was an ardent ecological driver. The oil change cost eat up your fuel savings. You can't take the car to a local mechanic as no one is trained on hybrids. Dealer maintenance is just too high. Looking at Jetta or Cooper now.