The 18-year-old, back in the cockpit for the first time since his record-breaking victory at the Spanish circuit, worked his way down to 1m 23.267s on soft tyres in the morning session as Renault's upgraded engine continued to offer plenty of promise.
"For me personally it was good to have the opportunity to get even more comfortable with the car," commented Verstappen. "I was able to try some new things and find ways to improve my performance. I learned a lot about the RB12 today, which is very, very positive.”
Stoffel Vandoorne backed up McLaren's strong showing by going second fastest using the supersoft rubber, the reserve driver spending much of the day trialling new parts on the MP4-31.
“The car felt good straight away today," said Vandoorne. "Of course, I had a few laps of adjusting to the car, but it definitely has progressed since I raced it in Bahrain. It’s been a positive and productive day."
Pascal Wehrlein, a late call-up for Mercedes, did similar work for the Silver Arrows and ended up third quickest, just ahead of Haas driver Esteban Gutierrez, who bolted on the ultrasoft tyres late in the day but set his quickest time on supersofts.
Ferrari youngster Antonio Fuoco meanwhile made the most of a late soft tyre run to move up to fifth overall, which left him ahead of Toro Rosso’s Daniil Kvyat, Force India’s Alfonso Celis and Renault’s Kevin Magnussen.
Kvyat said he achieved his main aim for the test - racking up the miles to better acclimatise to his new car following his shock switch prior to the Grand Prix in Spain. "It was quite an important day for myself today, as being able to get time in the STR11 was essential, and I now feel much more confident and ready for Monaco," he explained. "We completed a big amount of laps, all of which are useful for both myself and the team. Tonight we will analyse all the data we've gathered and we will already be able to use this valuable information in the next events."
Magnussen too said the test had definitely been 'positive' for Renault. "The car feels good and it was great to conduct such a wide variety of assessments as it shows we’re clearly making progress," he commented. "The power unit feels stronger and has better driveability and there are some other good improvements too."
The final two slots on the timesheet were occupied by Williams’ Felipe Massa – who like Alex Lynn on Tuesday carried out more running with the team’s unusual rear-wing – and Manor’s Jordan King, who caused one of only two red flags on the day when he ran wide at Turn 7 and dragged gravel onto the track.
Sauber were the only team not present at the test.
Unofficial Wednesday test times from Spain