Montoya looked good on his debut for McLaren in Spain

The Colombian, who has switched from Williams for 2005, was comfortably fastest at a major Formula One test at Barcelona's Circuit de Catalunya.

Montoya set a best lap of one minute 14.196 seconds; his former team-mate Ralf Schumacher, now at Toyota, was second fastest on 1:14.609.

"Juan Pablo's first day of testing went well," said Norbert Haug, sports boss of McLaren's engine partner Mercedes.

"But as usual during winter testing lap times do not mean a lot."

Montoya, who won the last race of the season for Williams, said: "It's been an exciting day and the first time I went out of the garage in a McLaren was special."

Montoya says goodbye with a win

Montoya managed 52 laps on Wednesday, and was more than two seconds faster than McLaren test driver Alexander Wurz.

Schumacher said the Toyota was "much better than I expected it to be".

Felipe Massa was third fastest for Sauber, ahead of Red Bull's Christian Klien in a rebranded Jaguar and Mark Webber's Williams.

Everything was new for me, but I was impressed with what I found Giancarlo Fisichella New Renault driver

Australian Webber set a best lap of 1:15.381 on his first full day's running for his new team.

He headed Ferrari test drivers Marc Gene and Luca Badoer, the second Toyota of Jarno Trulli and Giancarlo Fisichella, who was having his first run in a Renault following his switch from Sauber.

Fisichella said: "Overall, I am pleased with how things went.

"Although I didn't get out on the circuit until midday, we did over thirty laps and I was able to begin learning about the car, the engine and the tyres.

"Everything was new for me, but I was impressed with what I found: the tyre performance is good, and the engine was strong at low revs.

BAR step up search for F1 success

"The car is not yet balanced how I want it for my driving style, but we are going in the right direction and it is getting more comfortable. It was a good start to the week."

Wurz was next fastest, ahead of BAR's Jenson Button.