LONDON -- Susie Wolff was promoted to official test driver for Williams for the 2015 Formula One season on Friday, increasing her chances of becoming the first female racer on the grid since 1976.

Wolff will build on her three seasons as the team's development driver by taking part in the first two practice sessions at races still to be determined, as well as two test days. She will also conduct extensive simulator testing to help with the development of Williams' new cars.

If Valtteri Bottas or Felipe Massa were to miss a race next season, the 31-year-old Wolff would be first to step into the seat.

"This is another step in the right direction for me," Wolff said. "I am delighted Williams are recognizing my progression, hard work and it is performance that counts."

Italian driver Lella Lombardi was the last woman to race in F1.

Wolff drove in practice ahead of races in Britain and Germany this year, becoming the first female driver to take part in a grand prix weekend in two decades.

"She has steadily increased her time behind the wheel since she joined us in April 2012," deputy team principal Claire Williams said, "and her appointment as official test driver was a natural progression."