Car mount/dock for Nokia lumia 920

I have the charging ProClip dock, and custom vehicle mount. Works great, but I get a ton of interference from the cigarette lighter power....when plugged into audio jack.
 
My car doesn't have a flat dashboard . Hence the universal cube mount is not sticking on it. Neither does it stick to the windshield as the cube falls of due to the weight of 920 .
Can u guys help me finding the best mount for lumia 920 to use in my car.
I guess windshield mounts and vent clips are the only choice now due to dashboard not being flat.