You auto isn't 12v , it's more like 13.8 or more. You need a dc-dc regulator check the mp3 store. Some people have and had good luck(running straight from the batt). I myself have a SX280 (dell) that has a 12v input but, I'm still gonna put a regulator in the line. Use your own judgement but, if you're wrong you just fried your machine. Good Luck.