Pirelli's latest 2017 tyre development test was cut short on Thursday as bad weather hit the Barcelona circuit, meaning Pascal Wehrlein, driving a modified Mercedes mule car, only completed 31 laps.
Wehrlein is standing in for Lewis Hamilton, who chose to sit out the test in order to rest an injured foot ahead of the United States Grand Prix next weekend.
The track was damp to begin with following an overnight rain shower, but action soon began once the fog had cleared. Wehrlein completed 31 laps on the intermediate tyres, but his running was cut short during the afternoon as the rain returned.
Added to the 60 laps driven by world championship leader Nico Rosberg on Wednesday, Pirelli have completed 91 laps over two days.
"Obviously the weather hindered progress to some extent both today and yesterday, as is not entirely unexpected at this time of year in Europe," commented Pirelli's Paul Hembery.
"The same can apply to the early part of next year, which is why we are in favour of some guaranteed warm weather testing in 2017, before the season gets underway."
The next Pirelli test of the season will take place in Abu Dhabi with Red Bull from October 14-16.