I installed a ported subwoofer box in the trunk of my C220. The port fires directly into the cabin through the rear seat. I'm not familiar with your car, but on mine there is an arm rest in the middle of the rear seat. When the arm rest in lowered it exposes a vinyl panel. I removed this vinyl panel and replaced it with color matched speaker fabric. The sub port is directly behind this opening. The end result is great low end response without rattles or major modifications.