Which car should I buy?

OK here is my story I bought a MBZ ML 430 back on jan 1st 2006 which is the worst car buying experience I ever had I guess because I was so excited that it was the first that i was buying an MBZ the car had 60 000 miles and now that it has 100000 miles is not working properly and the waranty wont cover it so I'm stock with a car that doesnt work and paying 500 a month for having it in my garage doing nothing and I still owe about 18 000 on the car value is of 13 000 on the KBB so I dont know which car maker has a good deal for me or what can I do to get rid of this car without messing myself up.....any reconmendation is appreciated.thaks!!!