It's not really important that your coolant and brake fluid look clean and full.
Mercedes requires coolant to be replaced at 3 year intervals.
Mercedes requires brake fluid to be replaced at 2 year intervals.
Coolant not only raise the boiling point and lowers the freezing point, but it also inhibits rust / corrosion. When coolant gets old, it loses its ability to prevent rust, and actually becomes corrosive.
Brake fluid loves to absorb water (hygoscopic ??). Water build-up in your brake fluid is a bad thing. It decrease your braking performance, it allows the fluid to heat up faster, and it could allow your broke cylinders to rust.
These are the only two maintenance items that occur in time intervals instead of mileage intervals, and they cannot be neglected.
2001 E430, Bourdeaux Red, Oyster interior.
1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".