First you need to start a new game(when you haven't save anyone),
then save it,
then end game and open up your "documents" folder,
then open "German Truck Simulator",
then open the "save" folder,
then click on this saved game, where you want a cheat for it,
then click on "game" folder, select open it with a list,
then use "notebook" to open the file.
Now you only need to look for:
and change it to so many money how you want.
save it and close.
When you will start then the saved game where you have use the money cheat,
you will have so many money how you have change in notebook.
No fuel price:
You can get fuel for free. You only need to follow the steps:
1. Open your "documents".
2. Open "German Truck Simulator".
3. Open "save".
4. Open now the save, where you want to cheat for it.
5. Open "game" manually with notebook.
6. Now look for the line:
-total_fuel_price: 356 and set it to:
-total_fuel_price: 0, then you will not pay money, when you drive to the gas
7. Save it until you close it.
8. Load the saved game, where you have use the cheat.