Originally Posted by 1fastdoc
I hear several people saying that using a battery tender makes a difference but I don't see how. I assume you mean driveability.
I have an '11 M3 with a little over 8k miles on it. I drive 1.6 miles to work. 2.9 miles to the gym and then 1 mile back home. This is 5 days/week plus a few miles on the weekends.
So far it still starts fine, the lights are bright, the stereo is loud, the heated seats keep my ass warm, etc.
With prior cars when the battery goes bad it won't start. What's different with the M3?
Because you are putting your battery through a lot by driving such a short distance before you shut the car off. It doesn't have time to replenish.
More worryingly, I'd change the oil more often due to sludge concerns. You car (your oil) doesn't even have time to warm up before you shut it off.