The "part4.rar" suffix indicates this is part of a . To successfully extract the game files, you must have all parts (e.g., part1, part2, etc.) in the same folder and use an extraction tool like WinRAR or 7-Zip on the first part.
Implementation of branded JOST fifth wheels (trailer couplers), replacing previous unbranded variants. Gameplay Improvements: Euro Truck Simulator 2 v.1.45.3.0s.part4.rar
Added a option that automatically adjusts wiper speed based on rainfall. The "part4