Mercedes are an"invincible battleship" but their prolonged success in Formula 1 in unanticipated.

The German manufacturer made history last year by winning both championships for a sixth straight time, surpassing the great Ferrari team led by Michael Schumacher, though they would win the Constructors' title between 1999-2004.

Key to that success was the change to V6 hybrid engines in 2014, as they got a head start over their rivals, but even as others have improved, no-one has yet come close to stopping Mercedes' F1 reign.

“It’s been amazingly impressive and if ever you go to the HPP [engine factory] in Brixworth, you understand why," F1 chief technical officer Pat Symonds said via Crash.net.

“There are so many good people there, so well-financed, such good equipment, fantastically strong leadership from Andy Cowell.

“It (their continued success) doesn’t surprise me now [but] I didn’t anticipate it.

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“I think even if you go back to the V8 era, the Mercedes was the strongest engine and they didn’t always have it in the best chassis when they were really supporting McLaren, but as soon as it went into the Brawn, it won a championship."

With hybrid technology having so much room for improvement, that has enabled Mercedes to continue finding the engine gains to stay ahead.

Even so, Symonds admits the fact it has taken their rivals five years to close up is the most surprising part.  

"No, I wouldn’t have anticipated it," he said. “Perhaps more importantly, I wouldn’t have anticipated how long it’s taken for the others to catch up. They have caught up now.

“I think Mercedes would even say Ferrari have gone ahead, but it surprised me how long that’s taken.”

While their engine advantage is now gone, as an overall package, Mercedes has remained the best, and former team boss Flavio Briatore voiced a comment argument that it is the car, not the driver, which has been decisive to that.

“Mercedes is an invincible battleship,” he told Italy's Autosprint. “At least five or six drivers, including [Fernando] Alonso, would have won the title with their 2019 car.

“But I take no credit away from Hamilton because you still have to beat the teammate at your side.”