The majority of
car batteries are created by 3 manufacturers - Delphi, Exide and Johnson Controls Industries. Delphi makes some EverStart models sold in Walmart and ACDelco. Johnson Control Industries makes Duralast seen in Autozone stores, Diehard - sold in Sears, Kirkland - the Costco brand, Motorcraft - which Ford sells, some of the EverStarts, and Interstate. Exide makes Exide batteries, Champion, Napa and even a % of the EverStart batteries.
Read more:
http://wiki.answers.com/Q/Who_makes_car_batteries_in_US#ixzz1z7rZMRRC
I found the above statement and link online. I recently replaced the battery in my C4 with Interstate...I've used Interstate before and had good luck. I suspect many C4VR members have had good and bad luck from many of the brands listed above. It's interesting though IMO to find there are many brand names, but just three manufacturers.