Over 4,000 race fans enjoyed a stop-start day of testing at Barcelona today, as 18 drivers continued preparations for the start of the European F1 season, despite a plethora of red lights caused by spins and failures.

The only team missing from this week's major test is Midland, which is carrying out a solo test at Silverstone.

Heikki Kovalainen topped the time sheets, with Renault teammate, Fernando Alonso, third quickest, the Spaniard one of many drivers to cause a red flag.

With conditions close to what can be expected for the Spanish GP, Renault worked to analyse the behaviour of the R26/RS26 package for the Spanish event on 14 May.

Fernando Alonso, who will be driving for two days this week (today and tomorrow), worked on set up and tyre development. His programme was interrupted by electronic problems, which meant he completed a restricted number of laps, but these will be resolved for tomorrow.

Heikki Kovalainen completed significant mileage as he worked through his programme to assist the team's race preparation. He also focused on set-up and tyre development during his first day of running this week.

The Finn will be back in action on Friday, with Giancarlo Fisichella driving alongside Fernando Alonso tomorrow.

"We made good progress today with Heikki's car," said Christian Silk. "He adapted to the car and circuit quickly morning, which was important as he had not tested here for quite a while. We confirmed the set-up improvements we had found in previous tests, and he got through a lot of tyre work. Fernando was also very productive in the laps he was able to run. Electrical problems limited his running, but we nevertheless had a positive day overall."

Splitting the two Renaults was Rubens Barrichello, who was joined by Honda test driver Anthony Davidson.

The Brazilian began the day with a couple of set-up runs and having found a good balance on the car, he then began an aero evaluation. Meanwhile, the Englishman completed some early aero runs before beginning a chassis set-up evaluation. With the track improving throughout the morning, he found a good balance on his car and completed the planned morning test programme.

Rubens continued to work on his aero evaluation in the afternoon session, while Anthony spent the afternoon continuing the chassis set-up evaluation which he began in the moring.

Oliver Panis and Ricardo Zonta were on duty for Toyota as the Japanese team focussed on aerodynamics, tyre construction and electronics.

"It was a very good day in general," said the Brazilian. "We worked on short runs, concentrating on tyre testing and aerodynamics.

"This is the first time that I have driven the 'new' car in Barcelona, since it was released in Vallelunga," he added. "It was very difficult with so many drivers on the track to get a clean lap, but in the end, we had a good time and were happy with the results. The car is showing potential and we still have a lot to do, but we are definitely moving ahead well."