This answer is different for different vehicles. With the older models, like the E46’s, there is a sequence to be followed: oil service, inspection 1, oil service, inspection 2. And then the sequence is repeated again. In terms of parts, both an oil service and inspection 1 requires oil and an oil filter. An inspection 2 service includes oil, oil filter, air filter, micro filter, spark plugs (on petrol engines), and petrol or diesel filters (unless it’s in the fuel tank). With an inspection 1 service, more items on the vehicle is visually checked.
The newer vehicles have Condition-Based Servicing or CBS. This means that all the service items have been split up. Based on your driving style, and conditions, as well as time or mileage elapsed, the car will indicate when a service item is due. Service items are: vehicle check, oil service, spark plug service, micro filter service, brake flush, front brakes and rear brakes. Some diesel powered vehicles also include the diesel particle filter as a service item. The air filter is not regarded as a service item, but should be replaced at regular intervals. If the vehicle has an in-line fuel filter (as opposed to a filter in the fuel tank), it should be replaced at regular intervals.