All of these cars are different. On mine, fuel filter interval is 60,000 miles, spark plugs are 5 years or 100,000 miles, brake fluid is 2 years and coolant is 3 years. If you're having A and B services done at a place that knows Mercedes they will be on top of this for your car.
Since you have a W203 look for that forum in the sedans section and they might have some sticky threads to answer your question. Or you can use the search function or start a new thread there.
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