Hamilton pleased with new McLaren
Lewis Hamilton declared himself happy after his first drive in McLaren's new car despite lagging behind Felipe Massa's Ferrari in Valencia testing.
"It's a different feeling compared to the first lap of the first test day of 2009," said the 2008 champion.
"It's a positive feeling. I've kept a close eye on the development of this car. I've seen it evolve and had input into it which is very exciting.
"I got out smiling. The problems I had [last year] I don't have in this car."
Flaws in Hamilton's 2009 McLaren left him well off the pace last season. Although they were eventually resolved, allowing him to win two races, he was unable to defend his title.
But after completing 108 laps in the MP4-25 on Tuesday, he said: "This was everything I could have asked for from a first day. It's gone well.
"We felt quite comfortable with what we did, but obviously there is a bit of time we need to find and a lot of areas where we can improve.
"It's too early to say that this is a car that can challenge, but I do feel it's a huge improvement from the beginning of 2009.
"The encouraging thing is reliability. We've had two days and not really had any problems, and that's a huge plus for us.
"Ferrari seem very quick but we don't know what fuel loads everyone has got."
Brazil's Massa topped the times for the second day running at Formula 1's first major test of 2010 at the Ricardo Tormo circuit.
Hamilton was third fastest behind the Sauber of Japan's Kamui Kobayashi and 0.534 seconds adrift of Massa.
Headline lap times from testing are not necessarily an accurate indication of the pace of the cars, as fuel loads, tyres and track conditions can have a dramatic effect on performance.
Fast test boosts Massa's confidence in Ferrari (UK users only)
The Ferrari, though, has looked consistently quick throughout the two days of testing in Spain so far.
Massa recorded a best time of one minute 11.722 seconds, with Kobayashi on 1:12.056 and Hamilton on 1:12.256.
"I was doing some good, consistent times and many laps," said Massa.
"I think I was the driver who ran most today so I am really happy. I hope we carry on like this through the winter test, but also during the season.
"2009 was a difficult season. Lots of things changed on the rules, on the technical side and the political side.
"Now it is a little more clear to everyone and I'm looking forward to being more competitive."
Ferrari took until the fourth race of last year to register their first points of the season and finished fourth in the standings well behind Red Bull and Brawn.
Massa's own season was brought to a premature end when he suffered a fractured skull caused by a spring that fell loose from Rubens Barrichello's Brawn GP car during qualifying in Hungary.
Barrichello hopes to go the distance
His new team-mate, double world champion Fernando Alonso, is due to take over the car for the final day's running on Wednesday, when Hamilton will be handing the McLaren over to team-mate Jenson Button, the reigning world champion.
"He's a great guy and we have both got a huge amount of respect for each other and what we have achieved," said Hamilton of his fellow Briton.
"We'll push extremely hard to try and beat each other and hopefully in a positive manner to push the team forward."
This week's test is the first time the new 2010 F1 cars have run on the track, and all the major teams bar Red Bull are in Valencia.
Red Bull - who ended last season second in both the drivers' and constructors' world championships to Button's former Brawn team, who have been taken over by Mercedes - are waiting until the second test, in Jerez next week, before giving their car its debut.
Mercedes driver Nico Rosberg was fourth fastest for much of the day.
The surprise of the test so far has been the pace of the Sauber.
Spanish veteran Pedro de la Rosa was second fastest with it on Monday and his team-mate, the Japanese rookie Kamui Kobayashi, occupied the same position for much of Tuesday.
The team are back under the stewardship of founder Peter Sauber following the decision of former owner BMW to quit F1 at the end of last season.