user: Question: What fuel system does the Diesel engines model have?
Columns: ['Model', 'Engine', 'Displacement', 'Valvetrain', 'Fuel system', 'Max. power at rpm', 'Max. torque at rpm', 'Years']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Petrol engines', 'Petrol engines', 'Petrol engines', 'Petrol engines', 'Petrol engines', 'Petrol engines', 'Petrol engines', 'Petrol engines']
SQL:

assistant: SELECT "Fuel system" FROM "Table" WHERE "Model" = 'Diesel engines';