Spaniard Marc Gene thanked former employers Williams for doing him a favour after his first day as Ferrari test driver.
"Everything happened so quickly that I haven't had time to realise that I have joined the best team in the world," the 30-year-old told Italy's Gazzetta dello Sport newspaper on Wednesday.
"I needed only a few laps and several hours with the team to understand why they are the champions," added the Spaniard, confirmed in his new role on Monday.
"I haven't been here a day yet and I already feel at home."
Gene, testing at his home circuit in Barcelona, said Williams had given him plenty of notice they would not be retaining him after fours years as a tester and occasional racer for the BMW-powered team.
"I contacted the top teams and Ferrari were the first to respond," he said. "I don't know why Williams made their decision but, given how things have turned out, they did me a favour.
"Maybe I could have aimed for a drive but there are no doubts. It's better to be a Ferrari test driver than to drive for an uncompetitive team."
Ferrari, constructors' champions for the past six years in a row, won 15 of the season's 18 races with Germany's Michael Schumacher taking 13 victories on his way to an unprecedented seventh title.
Former champions Williams, fourth overall, won once.
