For the same reason so many have sprint boosters.

 

Well, Being same priced, I would buy 50 of these and non sprint booster, the sprint booster is Total Waste of $$


I will check into this piece of electronic stuff and post any useful info. I know of cars with Batteries located under the hood, so the the Grounding Cables helps the engine firing. but for BMw having the battery in the trunk, i think the effect is smaller.

but at least, I feel things works better

 

thanks for the info; any feedback on this battery replacement on Rayovac.