De Filippis had a poor result at the 1958 Portuguese Grand Prix in August. She qualified in last place, more than 15 seconds slower than the car ahead of her, and only lasted six laps before her engine failed. On 7 September 1958, she started her home Grand Prix at the Autodromo Nazionale Monza from last place. She completed 57 of the 70 laps before having to retire with engine problems. As the 14th and final retirement out of 21, she could be classified as finishing eighth.