My 2006 Cooper S is running great, but I think that the battery should be replaced. My car has the original battery, and there's been no problems. Chicago winters can be harsh, and at nearly 7 years of age, I am doing a bit of preventative maintenance. I just purchased a 47H5 battery from Advance Auto Parts. Reasonable price, as there is an online coupon. I hope it lasts as long as the original!