The combined mass of the car and the person is 1990 kg + 58.7 kg = 2048.7 kg.
The error interval for the combined mass can be found by adding the maximum possible error for each measurement. For the car, the maximum possible error is 0.5 kg (half of the rounding unit of 1 kg), and for the person, the maximum possible error is 0.05 kg (half of the rounding unit of 0.1 kg).
Therefore, the error interval for the combined mass is 1990 kg + 58.7 kg - 0.5 kg - 0.05 kg ≤ m