"Sutil's performance was more convincing than anything his fellow countryman Michael Schumacher produced in (the last) three years," Independent newspaper correspondent David Tremayne wrote.
Sutil ultimately finished seventh in Melbourne as his tyre strategy played out, but the 30-year-old told Auto Motor und Sport: "It is surprising how well it went.
"When I saw P1 on the pit board, it was quite a feeling."
Deputy team boss Bob Fernley, however, insists he was not overly surprised.
"During the testing, if you had analysed it, you could see the promise," he is quoted as saying.
First to seventh might then sound disappointing, but Sutil could not stop smiling.
"Considering that three weeks ago I didn't even have a seat and was only able to test for three days in Barcelona, it could hardly have gone better," he said.