Rosberg: Red Bull's biggest weakness vs. Mercedes is battery efficiency

Nico Rosberg believes the key difference between Mercedes and Red Bull-Ford's power units is not the combustion engine—it's battery management, an area where Mercedes currently excels.

Red Bull's first in-house power unit was declared the benchmark at both FIA evaluation thresholds, meaning it couldn't benefit from development tokens, unlike Mercedes and Ferrari. But Rosberg sees a clear weakness in Red Bull's package: battery efficiency.

Why it matters:

Under the current power unit regulations, efficiency is as important as raw power. Red Bull has built the fastest combustion engine from scratch, but its battery deficit could be the deciding factor in races. With development tokens limited, closing that gap quickly is critical for any title challenge.

The details:

• Speaking on the Sky F1 Show, Rosberg said: "They came from nowhere and built the fastest combustion engine out there. Where their weakness is, is in the whole battery energy efficiency."
• Mercedes' ICE is about 2% down on power compared with Red Bull's, but its battery performance is "incredibly efficient" and compensates for that loss.
• Rosberg insists Red Bull can still make rapid progress, praising its development: "They've done so incredibly well."
• Mercedes has paused W17 upgrades since Canada, when it introduced a package covering the front wing, floor, sidepods, bodywork and diffuser.
• Development resumes in Malaysia in early October with a new upgrade package; Baku is expected to bring no major updates due to the circuit's low-drag, high-speed layout.

What's next:

Rosberg is convinced Red Bull can close the gap and "challenge more consistently for race wins" before the season ends. Mercedes, meanwhile, will stay patient at Baku before introducing fresh performance in Malaysia.