My battery died and the dealer keeps asking me if I am leaving anything plugged in (cell phone, I-pod, etc.) or leaving something on (lights, radio, etc.) and I keep telling them no - doesn't the car record if something is left on so they can do a download and find out? If it matters, car is a 2008 Boxster S.

 

I believe some data IS logged... but it is powertrain related stuff (perhaps to void warranties)... and in the future, even crash related stuff (black box style)

But I don't believe the car stores any info on how it powers accessories. Hope it gets fixed soon

 

Be sure to remove the key out of the ignition also when you park your car in the garage, some people leave it in and some control modules wont shut down and it eventually drains the battery.