Mercedes has confirmed that it has dipped into its remaining power unit development tokens to upgrade its fuel system ahead of the Russian Grand Prix.
The championship-leading team is fending off a strong challenge from Ferrari – which spent three tokens this weekend to bring an upgraded engine to Russia – which will see Mercedes upgrade its fuel systems along with the introduction of a new Petronas engine oil.
Unlike Ferrari, which has had to provide new power units to both its drivers, Mercedes can simply upgrade the current engines as the fuel system is "outside the sealed perimeter", meaning it doesn't count as an entirely new power unit.
Mercedes has also confirmed that its customers: Williams, Force India and Manor, will receive the upgrade this weekend.
The spend leaves Mercedes with 11 tokens for the remainder of the season, five more than Ferrari, but three less than Honda and 14 less than Renault.
