The FIA's World Motor Sport Council last week ratified a rule change that ensures new manufacturers in F1 are given an extra power unit for use in their first season.

A new article 28.4b) of F1's 2015 Sporting Regulations, referring to the current four engine limit says: "With the consent of (and at the sole discretion of) the FIA, the number [of four engines]... will be increased by one for any driver using a power unit provided by a manufacturer or supplier taking part in his first Championship season."

Only fifth engine mentioned

While the rule would appear to leave the way open for Honda, the situation is complicated by the fact that both Honda drivers Jenson Button and Fernando Alonso already used their fifth engines at the Austrian Grand Prix.

The wording of the rule means it is not automatic that Honda will escape a penalty for when it uses a sixth engine, which is why it needs confirmation from the FIA about exactly what it can do in the future.

A Honda spokeswoman told Motorsport.com: "We do not know the details of how we gain back the Austrian penalties etc. We have to confirm the details going forward, now that the FIA has made its decision."

Hungary plans could change

Should Honda be told that it is free to use a sixth engine when it wants without penalty, then that opens the door for a new power unit to be used at the Hungarian Grand Prix.

The Japanese manufacturer could even elect to use some of its remaining engine development tokens there, as there would be no risk of the changes forcing a grid penalty on the tight and twisty track.

But until it knows its longer term strategy regarding how many engines it can use, it is unable to commit to its plans for the Hungaroring.

Honda's motorsport boss Yasuhisa Arai has been adamant for some time that tokens would only be used after the summer break, and he has not give any indication of a change of plan yet.

However, that does not mean Honda will not make a last-minute push to deliver improvements.

The Honda spokeswoman conceded that the situation was not set in stone yet though.

"We still have time until the Hungarian GP," she said. "Details change every day up to the race."