On his final day of pre-season testing, Romain Grosjean topped the timesheets in the Lotus E21 as the mixed weather conditions continue to confuse the pundits.

In the wake of today's session, which was book-ended by rain showers, a number of drivers, including Sebastian Vettel and Jenson Button, bemoaned the fact that the unseasonable temperatures are making tyre evaluations meaningless, though conditions are expected to improve for the final two days running.

On his last day of running before Melbourne, Grosjean focussed on system checks, temperature monitoring, data correlation, assessment of the performance of the car with its initial aerodynamic package and new rear suspension set-up evaluation.

"Even though the weather was far from ideal it was a pretty good day for us and it's certainly a better feeling to end the session with the fastest time on the board rather than the slowest!" said the French youngster. "We had strong reliability again today and the E21 feels good in all conditions, which is very promising for the season ahead.

"Of course, I wish I could have more time in the car before the season starts, but if we're in the same position on the monitors when we get to Australia I'll be very happy indeed."

"Today was far more productive than yesterday," added Alan Permane. "We debuted a new rear suspension variation, working on initial set-up in the wet conditions this morning, then switched to dry tyres in the afternoon to gather further data on the medium and soft 2013 compounds.

"Whilst circuit conditions are not as favourable as last week due to the recent rain, we were still able to show good pace and our initial findings from the new rear suspension are promising. Over the next two days we will be working on the updates we have for the E21; there's plenty of work left to do and we're hoping that the forecasts for better weather over the weekend are correct."

The damp track in the morning meant that Jenson Button's early running, like that of his rivals, was limited to aero mapping and mechanical evaluations. As the circuit dried out, he switched to the medium compound and ran through a number of different mechanical set-up iterations to find a good balance for MP4-28.

According to the team the programme was "efficient and productive", with Button going quicker on each subsequent run. By mid-afternoon, the Woking outfit was able to evaluate a number of upgrades over a series of longer runs. While these were interrupted by a late-afternoon red-flag stoppage, Button was still able to log some considerable mileage and incorporate a series of live pitstop simulations into the mix.

"I really don't know who's quick and who isn't," the Englishman subsequently told Sky Sports F1. Referring to the weather, especially the cold, he continued: "Dry weather for two days and circuit temperatures in the twenties, thirties is what we need because I haven't driven in that condition since Jerez.