Under the new rules, article 23.5 of the 2016 sporting regulations reads: “Only power units which are identical to the power unit that has been homologated by the FIA in accordance with Appendix 4 of these regulations may be used at an Event during the 2016- 2020 Championship seasons.”

This would appear to rule out manufacturers offering different specifications to customers.

However, at meeting of the technical directors in August, all were in favour of a proposal to allow the use of older-spec engines, subject to approval by the FIA on a case-by-case basis.

Article 1.2 reads: “These sporting regulations were published on 30 September 2015 and may only be changed after this date with the unanimous agreement of all competitors entered in the 2016 Championship, save for changes made by the FIA for safety reasons which may come into effect without notice or delay.”

Year-old engine supplies will be discussed at the next F1 Commission meeting, which is anticipated to be within the coming weeks.

Should the proposal gain Commission backing, it will be put on the agenda at December’s World Motor Sport Council meeting for ratification.

This would allow for Toro Rosso to use 2015-spec Ferrari engines next season, with the two parties closing on a deal.

Manor was allowed to use year-old Ferrari engines this season after it exploited a loophole in the regulations that required only concessionary permission to do so.

Appendix 4 of the technical regulations was tightened to ensure engine parity.