Lewis Hamilton joked that he was glad Mercedes detected a problem with its W07 Hybrid as its faultless pre-season programme was interrupted by a transmission failure.
Hamilton started his 70th lap shortly before lunch but his car came to a halt along the pit straight, the first - and only - time the outfit's 2016 car stopped on track during pre-season testing.
Despite the stoppage, team-mate Nico Rosberg was able to join the action an hour into the afternoon session, as Mercedes finished the eight days of testing having amassed 1294 laps of the Circuit de Barcelona-Catalunya, equivalent to 19 race distances.
"It's been an amazing two weeks for the team," he explained, after finishing the day in fifth spot.
"The guys have done an amazing job to get the car to where it is especially given the fact we've done more mileage in pre-season than we've ever done before.
"I'm kind of glad I broke the car at the end of my final run today because it's better to have found something now than in Melbourne!"
Rosberg finished at the foot of the times but focused on long runs and was encouraged by his stitn in the W07 Hybrid.
"This afternoon was probably the best the car has felt for me all the way through winter testing, so that was a really positive way to end the week," he said.
"We have done so many miles in the past two weeks, so we can feel well prepared for Melbourne, and the team has done an incredible job to build such a reliable car."