Rubens Barrichello says Williams's progress this year has left him both impressed and proud, and that the team could make a further step forward at Suzuka this weekend.
After an underwhelming start to the campaign, Williams made great strides over the summer, and having introduced a major new package in Singapore, Barrichello was able to qualify sixth for the night race - beaten only by the five title contenders.
That was scheduled to be the team's final upgrade of 2010, but Barrichello is delighted that more parts are coming for Japan.
"I'm very impressed, because at the beginning of the year we said Singapore was the last improvement on the car because we would then concentrate on next year's," he said. "And next year's is looking quite good, but they have brought one thing aerodynamically for here as well, so another step, which makes me really proud."
He compared the rate of development at Williams this year to the speed of progress at Ferrari when he was part of the team during its title-winning seasons in the early 2000s.
"When I worked with Ferrari it was really good for that, it was amazing how they could improve the car," said Barrichello. "I would say it's on the same level. I'm very proud of what we have achieved this year.
"If you just go back several months and look at Istanbul - Istanbul was dodgy, Istanbul was bad, the car was nowhere. But that difficult period, it wasn't like people were blaming each other. It was a good time when we got together and they started to listen even more to me. There was some good stuff that we made through the aerodynamics and some of the mechanical parts."
Barrichello said there was no point looking back and wondering what Williams might have achieved had its car started the season as competitive as it is now. The team is currently seventh in the constructors' championship.
"I don't think it's worth going there, because at the end of the day, how soon did Mercedes - for example - stop working on their car?" he said. "We have a car that I think is still a touch behind, but is getting really close. Renault has been really competitive as well, but they have tracks where they go better and worse. We're there."