The Ferrari academy driver, brother of Formula 1 driver Charles, topped the timesheets with a 1m29.366s set on Wednesday afternoon at the Spanish circuit.
Leclerc also led the morning session, and topped Tuesday morning’s rain-hampered running with a 1m40.202s, half a second clear of second placed Roman Stanek (Trident).
Championship leader Victor Martins finished the test second quickest for ART Grand Prix, just over 0.01s behind Leclerc, with Bahrain sprint race winner Isack Hadjar in third for Hitech GP.
Bahrain polesitter Franco Colapinto was fourth for series newcomers Van Amersfoort Racing, while Oliver Rasmussen ended up fifth in his first F3 outing of the year.
The Dane has replaced Jonny Edgar at Trident for his second campaign in the series after the Briton was forced to withdraw from the championship after being diagnosed with Crohn’s Disease.
All the fastest times of the test were set on Wednesday afternoon, which saw the best conditions of the two-day event.
Leclerc’s teammate Ollie Bearman led Tuesday’s running, taking advantage of the afternoon’s drying circuit to set a 1m33.009s, over 0.6s quicker than Campos Racing’s Josep Maria Marti in second.
Zane Maloney finished in third place for Trident, with Martins and Leclerc in fourth and fifth respectively having both previously led the timesheet.
The wet morning session caused one red flag after Hadjar ran into the gravel, having led the timesheet with a 1m42.047s.
Caio Collet (MP Motorsport) was next to go quickest, dipping below 1m42s, before Leclerc took the lead.
Despite more rainfall during the lunchtime break, the circuit dried out heading into the afternoon. Collet brought out the session’s sole red flag after stopping at Turn 4 before times tumbled in the final half hour.
Martins, Stanek, Rasmussen, Leclerc and Bearman had all dipped below 1m35s before Bearman came out on top.
Martins currently leads the drivers’ standings, having taken victory in the Bahrain feature race, with Leclerc and Bearman in second and third. ART lead the teams’ standings on 54 points, with Prema in second, seven points behind them.
F3 will have another in-season test in Barcelona from 15-16 April, before the series returns for its second round at Imola from 22-24 April.
