McLaren are quietly confident that their new car will enable them to mount a strong title challenge next year.
David Coulthard gave the new MP4-19 its first work-out with a "conservative" 47-lap test in Valencia on Tuesday.
And McLaren's managing director Martin Whitmarsh echoed Coulthard's view that initial signs had been promising.
"To debut a car in week 48 and have it setting reasonably competitive times on its first day is encouraging," Whitmarsh told BBC Sport.
"We're a strong and experienced team so no-one gets carried away. You don't win a championship in a day, but it was a very positive experience for everyone.
"The car will get quicker as we increase the rpm and work through a structured program.
"We are not there [in Valencia] with a mission to come away quickest, but we were immediately setting good and competitive times with high fuel loads and responsible tyre programs."
Kimi Raikkonen's title challenge faltered in 2003 as he was forced to finish the season with a development of last year's car.
And the radical MP4-18, which had been due for launch midway through the season, had to be shelved due to reliability problems.
Whitmarsh said the MP4-19 was an evolutionary step forward from the MP4-18's design, but had a new engine and incorporated a lower degree of technical risk.
"Geometrically the car at the front looks very similar to an MP4-18. Underneath the structure is quite a lot different. The rear-end packaging is noticably different," he said.
"We have an entirely new engine and we think we have a package which is going to be reliable."
Whitmarsh is confident the MP4-19 will be ready to do battle with rivals Ferrari and Williams when the season gets under way in Australia on March 7.
"The MP4-18 was the biggest step forward in terms of change we had ever taken. With the benefit of hindsight there was too much technical risk in it," he said.
"But anyone who saw it saw its pace and admired the engineering.
"It was clearly a very big step forward for us and we were able to take what we believe were the very positive and strong features and incorporate those in the MP4-19.
"There are a lot of big, strong teams in Formula One. It's difficult to win consistently and to win championships.
"You never know what they are going to do. It's certainly our expectation that we're going to be contending for the 2004 world championship, but you never know.
"I think we're going to be competitive. I think we can further improve on the car we have today and it's already a good step forward from where we ended 2003."