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.
Update 1.45 introduced several major additions and reworks to the game: Euro Truck Simulator 2 v.1.45.3.0s.part4.rar
New option to (the "X" symbols) for increased realism. The "part4
Implementation of branded JOST fifth wheels (trailer couplers), replacing previous unbranded variants. Gameplay Improvements: Optional Mod Support for the "Convoy" multiplayer mode
Euro Truck Simulator 2 - What is in the 1.45 Update Open Beta?
Custom city introductory cutscenes for and Hannover . Optional Mod Support for the "Convoy" multiplayer mode. File Context
The city of Hannover, Germany, was completely rebuilt from scratch with a fresh look and updated layout.