A complete frequency-modulated continuous-wave (FMCW) multiple-input multiple-output (MIMO) radar system is presented, incorporating a new and flexible system architecture. The baseband frequency can be freely adjusted by using separate transmit and downconversion chirp waveforms that are generated independently. This leads to various benefits, such as the possibility of removing harmonic distortions. In addition, the adjustability of the radar's lower distance limit aids in avoiding saturation in the receivers due to close targets or direct coupling. The radar system is fully modular, so that transmitter and receiver units can be added or removed, depending on the application. The radar was tested in a maritime environment and was found to reach a maximum range of 3km for a 50m long ship, and 1km for a 8m long boat. This is achieved with a maximum instantaneous output power of just 30dBm and an antenna gain of 6dBi in a field of view of 80°. In a 5x15 antenna configuration, the radar offers an average angular resolution of 2.4° and reaches an update rate of 10Hz for the complete radar image. The system operates at a frequency of around 3GHz and uses a bandwidth of 50MHz.