There is an official "free" method to play Version 1.48 legally. A is available on Steam. While it restricts the map to a small portion of the game (usually limiting the truck dealership and accessible cities), it allows players to test the v1.48 engine performance on their hardware before purchasing.
While the term "free" is common in search queries, downloading the game from third-party sites carries significant risks: Euro Truck Simulator 2 system requirements - Can You RUN It euro truck simulator 2 v14810 free
– this is the safe, official method.
If you don't own the game yet, you can still experience it for free through official methods: There is an official "free" method to play Version 1