Renault makes upgraded F1 engine available for United States GP

Renault had yet to dip into its allocation of 12 engine development tokens so far this season, but it is understood Renault has now used a "significant" amount of tokens, close to its full allowance.

The decision on whether or not to use the latest spec will be made jointly with Red Bull at Austin.

Any change will incur a grid penalty as Red Bull's Daniel Ricciardo and Daniil Kvyat have already exceeded their engine allocations.

Renault will make the previous spec, used in Russia, available should Red Bull decide against using the upgraded engine.

It is understood Renault's other customer Toro Rosso, which is close to a deal to use 2015-spec Ferrari engines next year, will not run the Renault upgrade at Austin.

The Renault updates are focused on the internal combustion engine (ICE), with some changes made to the turbo, all of which form part of the French manufacturer's preparations for 2016.

It is understood the Austin update has been validated, having completed a full cycle on the dyno to sign it off for reliability.

Renault will have a few tokens left following this update, however it is unlikely the French manufacturer will use the remainder of its allocation given only three races remain after Austin.

Regardless of whether Red Bull uses the new engine or not, Renault is pushing on with its development plans for next season as it looks to close the deficit to Mercedes and Ferrari.

It remains unclear whether Red Bull will use Renault power next season, with the two parties involved in talks as the former is currently without an engine supply for 2016.

Meanwhile, Renault is locked in talks with Lotus to make the Enstone-based team its works outfit next term.