I use a Group 26R in my '88 190E 2.6. It's smaller/lighter/cheaper than any OE replacement Group 48, but I never have to do a cold start below freezing.

The currently installed 26R was made by Johnson Controls, and I bought it from Autozone, but same JC battery is generic to many "brands" - just a different stick on label.

It's 15 years old and cost 40 bucks back in '01, but current replacements are typically a little over $100,

Battery prices have really skyrocketed in recent years.

Duke