However, the 28-year-old German said he will not be the official taste-tester, after both he and teammate Lewis Hamilton lost weight over the winter in preparation for the heavier technical regulations.
"We had a bit of a battle to see who has lost more," he admitted.
For both Hamilton and Rosberg, things seem to be turning out well for 2014.
"The car seems to work well with my driving style," said Hamilton, amid paddock suggestions the new silver W05 is clearly the class of the new grid.
Those who have seen the Briton face-to-face at the Jerez or Bahrain tests say Hamilton has visibly lost weight.
"I miss Aunt Jemima pancakes. It's been no pudding at Christmas and only boring food and water," the 2008 world champion is quoted by La Gazzetta dello Sport.