Force India's Sergio Perez believes that the power advantage of Mercedes' engine has been virtually wiped out by Ferrari and Renault's progress this year.
The German manufacturer has been in a league of its own on the power unit front since Formula 1 ushered in the era of V6 turbo hybrid engine in 2014.
But Perez reckons that Ferrari, and also Renault to a certain degree, have caught up with their respective development leaping forward this season.
"I definitely think that Ferrari is at the same level as Mercedes, and Renault is more or less there," explained the Mexican.
"We only have the advantage over Honda."
Perez insisted that F1's new-spec cars, characterized by their increased downforce, have put the onus on the engine this year.
But racing with similar power has only made Force India's task of fighting in the ultra-competitive mid-field all that more intense.
"This year, with these cars, the engines are much more important than in the past, because the amount of time you spent at full throttle was a lot less [last year] and the amount [of energy] you recovered was also a lot less," explained the Force India driver.
"Definitely Ferrari and Renault have done a massive step forwards to catch Mercedes."
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