Global Motorsport Media
Attacked by armed bandits outside the circuit a year ago, Jenson Button on Thursday had trouble gaining entry to Interlagos.
Express newspaper reports that even Bruno Senna, whose famous uncle Ayrton was revered by Brazilians, couldn't penetrate the tighter security in 2011.
"We were saying 'We've got the FIA press conference, will you be paying our fine?'" Button told reporters on Thursday.
Security is always a point of interest in Sao Paulo, with Germany's Bild newspaper amused to reveal the armoured Mercedes with bulletproof tyres used this weekend by Michael Schumacher.
And Thursday's usual autograph session was called off.
This is my sixth time here and nothing has ever happened to me
Police escorts have been made available to all the drivers, but Mark Webber told the Associated Press: "I'm still driving to the track on my own. No changes for me."
And world champion Sebastian Vettel insisted: "This is my sixth time here and nothing has ever happened to me."