Its actually very simple how the xenons work, they use your regular 12 volts, and there are ballasts (kinda of like transformers) that give a boost of power to your xenon bulbs (a bulb costs like $200), I had to change my fuse from 7.5 to 15 because of the ballasts. I love my xenon lights, they will last me a lifetime of the car, and it makes driving at night or when it rains with ease. if he can afford the 2003 ml350 I recommend that because alot of the bugs are fixed out from the older models.