Deni

I have a low knocking noise in the back of my Sportivo. It is more like a rumble. Sounds like something loose in the boot like the spare wheel but I have had everything out of the boot and the knock continues. Have had it into the servicers twice but they have not fixed it. They tightened up the resr suspension last time but it did not fix the rumble. Has anyone solved a similar problem with a Sportivo?