The Guernseyman – a three-time WTCC champion and winner of three races to-date in 2010 – edged out Chevrolet’s Robert Huff by just 0.08s at the end of the half-hour session.
Priaulx’s BMW team-mate, Augusto Farfus, finished in third position on the timing sheets, ahead of the quickets SEAT belonging to local boy Tiago Monteiro, who will be eager to impress in front of his home crowd.
Brit Colin Turkington finished a surprise fifth-quickest in his privately-entered BMW (pictured), marking him as the leading Independent Trophy driver on the timesheets in what is his first WTCC outing of the season.
2010 WTCC Round 5 Portimao Test Session Times:
[Original image via FIA WTCC official website]