The Yakima Lowrider rack system is designed to install on the 2000 Mercedes ml 320 roof rack siderails nicely. The Yakima Lowrider car rack system includes four Yakima Lowrider towers that connect to the side rails and a pair of strong Yakima round cross bars (you'll want to get the 58 inch bar length for your mercedes ml320) that connect to the four Lowrider towers. The Yakima Lowrider system provides the base platform that will allow you to then connect any of Yakima Racks gear carriers right to the pair of Yakima crossbars.
I'd recommend also visiting
these Mercedes Benz car rack pictures or
these various Mercedes roof rack system pictures as further resources.