McLaren still have "room for improvement" with their car, Button added.
Team changes not distracting - Button
"I like driving it," he said. "It is a nice car to drive. There is nothing that scares me with it but I still feel we can do a lot more with it than we are at the moment, and that's the exciting part, that we're not at the end.
"We're not ready to go racing yet. There are still interesting things that we have to try over the next couple of days."
"Generally we are happy with the balance of the car," he said. "I think it is a better starting point than we had last year.
Button's stats and facts
Williams, Benetton, Renault, BAR, Honda, Brawn
Grand Prix debut:
"It is very difficult to know in terms of pace where are.
"We have a rough idea, it's fine, we are happy with the balance and the way the car behaves but whether that is enough we don't know at this stage. It will be close until the end and we are not even at the beginning."
Ferrari's Fernando Alonso, who narrowly missed out on the title last year, said he was optimistic he could have a strong season and fight for the title.
"I don't see any reasons to not think so," Alonso said, "because last year it was a very difficult winter, we were completely lost and with that car we fought for the world championship all the way to Brazil.
"We now have a car that is responding well to what we change, a car that is doing what we expect the car to do.
"We know we are maybe not the quickest still but the starting point or the potential of this car is there.
"Last year it was a dream to make that car work. This year to make this car work I think will be much easier."
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.