Over the two days and an impressive 180 laps, the 25-year-old was at the wheel of a 2012-spec Sauber C31, but it was not wearing the Hinwil based team's usual dark grey livery.
In fact, it was Sauber's very first outing at Fiorano since 2005 with Jacques Villeneuve.
The man paying for de Silvestro's F1 programme is Imran Safiulla, according to the Swiss newspaper Blick.
It emerges that de Silvestro will actually do no fewer than 10 test days this year, with the next outing to take place at Valencia, Spain.
"It's not the cheapest thing in the world," said Safiulla, "but we can build something for the future."
Safiulla is a wealthy industrialist who has supported de Silvestro's racing efforts since 2006, including buying into the Indycar team KV.
At Fiorano, Sauber's 2012 car was painted in a special white, blue and green livery, with 'Clean Air Energy' and 'Hybrid' decals, although the car was V8-powered and not equipped with KERS.