I made a 'pre-emptive strike' on battery replacement for my 2013 R55 (after a couple of years of low voltage readings and some recent 'odd' electrical behaviors). ACDelco, Made in Germany (Bosch, I imagine). 60AH (instead of the 70 on my old battery). With a coupon Amazon was offering, it cost $135, shipped via UPS. ACDelco 47AGM Professional AGM Automotive BCI Group 47 Battery