By Alan Baldwin
LE CASTELLET, France (Reuters) - Formula One world champion Lewis Hamilton and other drivers using Mercedes power units started French Grand Prix practice with new engines on Friday but the German manufacturer kept a lid on the details.
The latest specification engine had been due for introduction in Canada two weekends ago but that was postponed at short notice due to concerns about an unspecified "quality issue".
That left four times world champion Hamilton, now a point behind Ferrari's Sebastian Vettel after seven races, at a disadvantage to rivals who had engine upgrades for the race in Montreal.
With drivers allowed only three engines a season before penalties are applied, Hamilton and Finnish team mate Valtteri Bottas were always going to get fresh ones having completed the lifespan of the ones they started the season with.
The question was whether it would be the planned upgrade or the same specification as the previous one, which would mean being locked into that for the next seven races.
"All six Mercedes-Benz powered cars have been fitted with fresh Turbocharger, MGU-H and internal combustion engine at this event," a Mercedes team spokesman said.
"More info to follow about specification after FP2 (second practice)."
The other Mercedes-powered cars are those of Force India's Mexican Sergio Perez and Frenchman Esteban Ocon as well as Williams' Russian Sergey Sirotkin and Canadian Lance Stroll.
Hamilton shrugged off concerns about the engine when asked on Thursday.
"The fresher engine this weekend will be great as it will have more power than the one I used at the last race," the Briton told reporters.
"I trust the team, and if we have to use the older-specification engine, I am not worried."
(Reporting by Alan Baldwin, Editing by William Maclean)