By Alan Baldwin
BUDAPEST (Reuters) - Double Formula One world champion Lewis Hamilton completed a Hungarian Grand Prix treble on Saturday with the fastest lap in final practice after also dominating the previous two sessions.
The Briton's best lap was 0.098 quicker than second placed Mercedes team mate and title rival Nico Rosberg, with the German's car coming to a halt at the end of the pit lane in the final minute.
The German climbed out before helping his mechanics roll the car back.
"It seemed like the engine stalled," Mercedes technical head Paddy Lowe told the BBC.
"We don't know more than that at moment, but it was not planned. We found a few issues last night which we were able to correct and he started in a bit better place today and we saw that in the lap times."
Hamilton, who set a best lap of one minute 22.997 seconds, has won four times previously in Budapest and will be chasing his ninth pole position in 10 races. He leads closest rival Rosberg by 17 points.
Ferrari's Sebastian Vettel was third fastest, but Finnish team mate Kimi Raikkonen was sidelined by a water leak and was only 16th, while Russian Daniil Kvyat was fourth for Red Bull.
Force India got both their cars back out on track after sitting out Friday's second practice following Mexican Sergio Perez's big crash in the opening session.
Nico Hulkenberg was sixth fastest while Perez was 15th on the timesheets.
(Reporting by Alan Baldwin, editing by Amlan Chakraborty)