The German was speaking to reporters after completing some tests in the vehicle.
"The first time I jumped into the car for the seat fit - checking the position, checking your pedals, see if everything works - I think it was the same for Mark [Webber, teammate] and myself, we felt extremely comfortable," said the 24-year-old.
"Everything went well and we got our position, comfortable position, fairly quickly. The RB8 was pretty straightforward, so we hope it continues that way.
"It would be wrong to go into this season and expect 2011 to happen again, as in getting into the lead early and having a very big gap to other competitors. I think it will be very, very tight this year."
Vettel joined Red Bull in 2009.