Mercedes commits to latest-spec engine

There has been speculation since the Barcelona tests that Mercedes was concerned about a potential problem with its crankshaft, which could have forced it to delay using the latest specification of power unit.

But a high-level source at Mercedes has said such claims are 'bullshit', and that it is sticking to the plan for the works team, plus customers Force India and Williams, to run the updated version that Lewis Hamilton and Valtteri Bottas evaluated in the final test.

Mercedes has made a big change to its power unit for this season and there have been rumours that it has been producing up to 70 bhp more on the dyno, but that did not seem to be borne out by its performance in testing.

It appears, however, that Mercedes may have been running with its engines in a more conservative mode in Spain, which has allowed it to trial experimental parts and manage components it is not yet convinced need to be brought into action.

One issue that is understood to have emerged in testing was a problem with the coupling of the MGU-K to the power unit, but Mercedes has been sorting solutions to this to ensure what it brings to Australia is bullet proof.

With F1's engine token system having been abolished this season, major updates are now possible when any new power unit is brought in to use, so anything not ready to run now can be introduced later in the campaign.

If Mercedes was running in a more conservative mode throughout testing it could explain why Ferrari, which ran a single power unit for the entire two weeks, may have appeared to hold the edge and why things could be different in Melbourne.

Equally, Mercedes may feel it is not yet comfortable enough to unleash the full power of its engine, so its full potential may not be seen for several races.