Rees was born in São Paulo. In late 2003, he was given a private test by Mercedes-Benz on the Portuguese circuit of Estoril. On December 11, 2003, Mercedes-Benz had organized a Formula 3 test among its official client teams of the Formula 3 Euroseries. Only six drivers were selected to take part in the test: Fernando Rees, Robert Kubica, Jamie Green, Bruno Spengler, Alexandre Premat and Adrian Sutil. In the single test day, Rees topped the time sheets driving the ASM Mercedes-Benz car. Later in the same year, Ron Dennis picked the ASM Mercedes-Benz team for Lewis Hamilton to drive in the upcoming Formula 3 Euroseries championship, and Rees was forced to look elsewhere to compete.