Mark Webber topped the timesheets on the final day of testing at Barcelona, as the predicted rainfall prevented little running for much of the day. After lunch the sun began to break through, however, intermittent showers meant the track never fully dried and consequently the Australian's time - set early in the morning before the rain arrived - was never seriously challenged.

Because of the conditions, Webber never got to try the 2009-spec tyres. But when the track was dry, he was able to run some new aero components.

"Despite the weather shortening our programme today, this has been a good four-day test," said Chief Test Engineer Ian Morgan. "We were able to acquire plenty of data from various new aerodynamic components and the results were positive. Some of these new developments will find their way onto the car for the Spanish Grand Prix."

Heikki Kovalainen (above) joined McLaren for the final day of the test. Like almost all of his rivals, the Finn sat out the morning session. The short let-up after lunch saw him take to the track for 40 minutes before a thunderstorm arrived, followed by hailstones. When this cleared, the Woking team carried on testing between the showers with very little running in the dry.

Third quickest was fellow-Finn, Kimi Raikkonen, who completed 33 laps in total, most of them in the wet. Only in the final hour was it possible to fit dry weather tyres.

The Maranello outfit's preparations for the Spanish Grand Prix continue at Maranello with the analysis of all the data gathered at this test and with the shakedown of the two cars that Felipe and Kimi will use, taking place at the Fiorano Track on Wednesday 23rd April.

For BMW, Robert Kubica continued to work on setups and aerodynamical solutions for the forthcoming Grand Prix. When the rain set in again the German team took the chance to collect more data with the car running on wet tyres. Although the heavy rain affected the team's work, it claims to have made good progress in further developing the F1.08.

Having complete a single installation lap in the morning, Jenson Button waited until the afternoon before completing a further 41 laps. "It's unfortunate that my day in the car this week coincided with the bad weather that we have experienced today," said the Englishman. "I was only able to complete 42 laps, mostly on wet tyres, and could not really gather any information from those laps. Thankfully the team had three good days of testing earlier in the week so we are well prepared for the race next weekend."

Kazuki Nakajima was the busiest man today, completing 62 laps. However, an engine failure marred Williams day.

"Kazuki took over from Nico for the last day of the test and concentrated on set-up for the Barcelona race," said Test Team Manager, Dickie Stanford. "Unfortunately, we lost a lot of track time this morning due to torrential rain which prevented any of the teams covering any mileage until after lunch. We were able to get some running in this afternoon using the intermediates and then we covered a few laps on the dry tyres to complete our prep work for the race."

Completing just one lap less that Nakajima was Nelson Piquet, who was back in action for Renault. The French team had planned to run slick tyres in the morning. But with the poor weather conditions it was forced to revise its plans as it was not until late in the afternoon that a dry line appeared.

However, the French outfit made the most of the limited running to give Piquet some further experience on wet weather tyres. Despite the loss of valuable track time today, the team says it has enjoyed "a productive week" and "achieved most of the objectives for the test".