The invention relates to the technology of gasoline direct injection (GDI) in automotive engines. In this context, the invention provides a method for maximizing the formation of deposits in injector nozzles of GDI engines, said method including at least one test cycle, each test cycle including at least one testing step in which a predetermined condition of speed and load of the GDI engine is maintained for a specified period of time, wherein, in said cycle, in at least one testing step, the engine speed is maintained between 1300 and 3700 rpm, the engine load is maintained between 10 and 80% and the specified period of time is from 10 to 200 minutes. Thus, the method of the invention is able to reproduce severe conditions of deposition of material in a few days, so that, in a short period of time, the test fuel can be assessed for tendency to form deposits.