The 26-year-old defending triple world champion, who is seeking his first win in Hungary, twice outpaced his Red Bull team-mate Mark Webber in sweltering conditions at the Hungaroring. (Agencies)
His second performance in the afternoon saw him clock a lap in one minute and 21.264 seconds that lifted him clear of Webber by just four-hundredths of a second in a closely-contested contest at the top.
It was almost demonstration driving by the pair as they confirmed Red Bull's superiority in the conditions to the dismay of those, including Ferrari and their fans, hoping to find a way of halting their express charge towards another title.
Vettel, in particular, appeared to relish his car's performance and justify his claim that he needs no motivation to carry on racing. "I don't think much, I think that helps," he quipped.
Romain Grosjean was third fastest for Lotus ahead of two-time champion Fernando Alonso and his Ferrari team-mate Felipe Massa.
Alonso recorded the first win of his career in Hungary while Massa suffered the blackest day of his at the circuit when he suffered serious head injuries in 2009.
Lewis Hamilton, the 2008 champion, was eighth fastest after a day spent struggling with the new Pirelli tyres. He finished just ahead of his Mercedes team-mate Nico Rosberg, Kimi Raikkonen of Lotus and Jenson Button of McLaren.
Adrian Sutil, celebrating his 100th Grand Prix this weekend, was 10th for Force India ahead of his team-mate Paul Di Resta and 12th placed Sergio Perez in the second McLaren.
Red Bull had also topped the times in torrid heat during the morning before the sun rose high in the sky to lift the air temperature into the mid-thirties and take the track beyond 40 degrees Celsius.
The 26-year-old defending triple world champion, who is seeking his first win in Hungary, twice outpaced his Red Bull team-mate Mark Webber in sweltering conditions at the Hungaroring.