The Hungaroring's track record was broken for the second day in a row as Mercedes protege George Russell clocked the fastest time of Budapest testing as F1 signed off from track action for three weeks.
Ferrari tester Antonio Giovinazzi had set a new unofficial benchmark with a 1:15.6 on Tuesday but Britain's Russell lowered that by a tenth on the same hypersoft tyres on Wednesday afternoon, stopping the clocks in a record 1:15.575 time.
The 20-year-old, who leads the F2 championship, has strongly been linked with race seats at Williams and Force India for 2019 in recent days.
"We did some runs on the hypersoft tyre, which was an incredible experience for me," said Russell, whose programme included work on brake developments. "I had never driven that tyre before, nor a Formula 1 car in anything other than a race setup. That was a great experience and it puts a smile on my face that we achieved the fastest lap ever around the Hungaroring."
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Kimi Raikkonen had set the morning pace for Ferrari and nearly matched Russell's time in the final 10 minutes of running on hypersofts, coming up 0.074s short in second place - not that the Finn was in any way perturbed.
"In the end, it's not that different to a Friday at a Grand Prix, when you try out various solutions," said Raikkonen. "And that's why, being a test, the lap times don't mean much."
The other team in F1's Big Three, Red Bull, were third but adrift of their usual rivals by 1.4s as simulator driver Jake Dennis completed his second day of testing in the RB14 this year.
Mercedes, Ferrari and Red Bull all racked up more than 100 laps apiece in a usual data-gathering exercise for when what has proved a fiercely-competitive 2018 season resumes at Spa on August 24-26.
Day One pacesetter Giovinazzi switched from Ferrari to engine customers Sauber to conclude the test, with the Swiss team potentially offering the Italian a route to a full-time F1 seat next year. He moved up to fourth quickest during the afternoon session, although his best time in the C37 was some 1.9s slower than his time in the Ferrari from Day One.
Nikita Mazepin was fifth for Force India but completed the fewest laps of anyone, 51, and stopped on track during the afternoon.
Williams reserve Robert Kubica finished the morning second to Raikkonen, but slipped to sixth at the end of the day as he completed his latest outing in the team's troublesome FW41 car. Williams, marooned to the bottom of the Constructors' Championship with just four points, had spent the opening day collecting data on the 2019 regulations as they tried a new-look 'simplified' front wing.
Kubica's 1:18.451 time from 103 laps was fractionally faster than McLaren's Lando Norris, who continued in the MCL33 for a second day and added 73 laps to his tally.
After crashing out late on during Pirelli tyre testing duties on Tuesday, Sean Gelael was back in the Toro Rosso but this time focusing on work specific to the team and his STR13 sported an array of aerodynamic rakes earlier in the day. He racked up 122 laps.
Toro Rosso's race drivers, Brendon Hartley and Pierre Gasly, shared tyre-testing duties in the team's other car and completed 67 and 75 laps respectively.
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