McLaren stepped up their preparations for the new Formula One season with the track debut of their new MP4-21 car on Monday.
Spanish test driver Pedro de la Rosa said first impressions of the Mercedes V8-powered car that replaces the V10 one that took 10 wins last season are good.
"It is of course too early to really understand its potential and we need to put a lot more laps on it," he said in a team statement after the first lap at Barcelona's Circuit de Catalunya.
The team, runners-up to champions Renault last season, have around 20 days of track testing before the cars have to be flown to Bahrain for the March 12 season-opener.
McLaren F1 chief executive Martin Whitmarsh said the team has taken a major step forward with the running of the new challenger.
"The anticipation within the team as to how competitive the new car will be is great, particularly given the pace of our 2005 racer and the level of work that has been put into the MP4-21 project," he said.
Whitmarsh said the team planned an "aggressive schedule of upgrades" to the car before Bahrain.
Colombian Juan Pablo Montoya will drive the new car at the Spanish circuit on Tuesday and Wednesday with Finland's Kimi Raikkonen, winner of seven races last year, testing on Thursday and Friday.
McLaren have only one complete new car ready for testing and the second is due to start testing in Valencia during the week starting February 13.