Max Chilton surprisingly managed to put minnows Marussia on the top of the time charts while troubles afflicted championship leader Mercedes' chief rivals on the first of the two-day in-season test in Barcelona as frequent showers interrupted the session on Tuesday.
The Briton's fastest time, registered when the track had dried up, was just over three seconds quicker than his own time set during qualifying for the Spanish Grand Prix on Saturday and just 1.2 seconds slower than the pole position benchmark recorded by Mercedes' Lewis Hamilton.
However, Chilton's lap came on the supersoft tyre, the quickest of the four slick compounds across Pirelli's range, during a qualifying simulation. Tyres nominated for the Spanish GP weekend were the hard and medium rubber, the latter of which served as the one to use to set grid position.
Marussia also topped the timesheets as others limited their running owing to a wet and damp track that was the mainstay for about half the day while the other half was dedicated to running setups and upgrades on the cars.
Cooler temperatures and inconsistent conditions didn't encourage the field either.
ISSUES FOR FERRARI AND RED BULL
"It felt more like autumn," reported Ferrari, which managed a paltry 20 laps.
The Italian team, struggling to challenge the frontrunners this season, made little progress after Kimi Raikkonen returned to the garage after just a few corners because of a power unit failure. The Finn emerged out on the track later in the afternoon but caused further delays after he spun at Turn 4, necessitating the floor to be replaced.
Hamilton, who dominated the Spanish GP weekend to win from pole, was third, two-tenths off the pace and suggesting the times were far from representative.
Red Bull was tenth quickest in the hands of test driver Sebastien Buemi, five seconds slower than the top time, with the team ending the session early due to a gearbox failure, a problem that had affected Sebastian Vettel during qualifying at the track on Saturday.
Caterham too ended its session early after Kamui Kobayashi went off in the barriers at Turn 3 pretty hard in the final half an hour severely damaging his car.
"I'm sorry for the guys in the garage who now have a long night ahead to fix the car, but the only good thing is that it was at the end of the day after we'd got through most of the runplan," Kobayashi said.
Sauber and Toro Rosso tested 2015 tyres for Pirelli, a requirement as per the regulations this season, assessing both the slick and intermediate tyres.
||Giedo van der Garde