If you prefer not to use a pre-made mod, you can manually adjust the fuel capacity by editing the game's definition files: Use the scs_extractor.exe tool to open the def.scs file.
: Some versions increase the capacity to 2,000 liters for all standard SCS trucks.
: Extreme versions found on the Steam Workshop can increase capacity to 5,000 liters or even up to 50,000 liters to eliminate the need for frequent refueling.
Truck's fuel tank capacities are, actually, too unreal? - SCS Software
If you prefer not to use a pre-made mod, you can manually adjust the fuel capacity by editing the game's definition files: Use the scs_extractor.exe tool to open the def.scs file.
: Some versions increase the capacity to 2,000 liters for all standard SCS trucks.
: Extreme versions found on the Steam Workshop can increase capacity to 5,000 liters or even up to 50,000 liters to eliminate the need for frequent refueling.
Truck's fuel tank capacities are, actually, too unreal? - SCS Software