Unit 4 is the new MTS trailer mainly intended for track events. It has a large office at the front with seating for about 8 people with sofas, tables, Smart TV, air conditioning and other amenities. It has a side staircase for access.

The rear part has two loading areas, one on the lower floor for machinery, material stock or vehicles and the other on the upper floor for formula type vehicles or material stock. A rear platform lift allows quick access to both floors.

This trailer can mount two 8×12 tents, one on each side. The canvas-roofed tents can also have canvas sides, ideal for tyre services, cleaning or vehicle maintenance, or an aluminium structure with transparent methacrylate panels with access through sliding doors.

The trailer will normally carry a vehicle (Smart Two) to transport the drivers once they arrive at the event.