Under normal driving Mercedes call for changing the engine oil (synthetic) and filter change every 12,000 miles along with a general inspection.
24,000 is a more comprehensive inspection, engine oil and filter and cabin air filter and wiper blades.
Air filter at 30,000 miles.
36,000 is a general inspection and engine oil and filter change.
48,000 repeat of 24k service
60,000 miles is a comprehensive inspection, engine oil and filter,air filter, and Fuel filter.
Spark plugs are not called for replacement until 100,000 miles.
I think all these intervals are too great. Are there any Independent Mercedes shops in your area or German car specialists? If so ask there advice.
I did find the service schedule for the 2000 Model Year ML
http://www.mbusa.com/mercedes/data/pdf/maintenancebooklet...