The French car manufacturer has been accused of having potentially broken F1's testing restrictions by running a full-size car on a rolling road with windtunnel capabilities at the Austrian AVL facility.
However, it has emerged that the six-day test was not as sophisticated as had been originally suggested - and instead took place on a normal engine dyno facility, as is allowed.
Renault's head of track operations Remi Taffin made it clear that the dyno test - which did not involve a rolling road - took place only because its facilities at its Viry-Chatillon base were already at maximum capacity.
"As far as we were concerned, it was to support Toro Rosso and try to get one more way to close the [performance] gap that we had at that point," he explained.
"Any dynos that would be available we could use - so we took the opportunity. It was just trying to get more dynos than what we had in Viry."
Interest in the dyno test surfaced this week when an anonymous letter was sent to the FIA, Ferrari and Mercedes suggesting that Renault and Toro Rosso had broken the regulations in conducting the dyno test.
The letter said: "I believe these extra test sessions gave Renault Sport and this particular team an unfair advantage over the other competitors.
"It is also my understanding that such practice is illegal and against the various articles of the 2014 sporting regulation published by the FIA and I am informing you in the interest of F1 fairness and safety."
Rival teams do not believe there has been any unfair play, though, although the FIA is still looking into the details of the situation to ensure that the rules have been followed.
An FIA spokesman said: "We are still investigating and when we will have all the details we will produce our answer."
The letter suggested that test driver Antonio Felix da Costa was sitting in the car at the time, and that there has a car fire, but both suggestions are believed to be incorrect.
Taffin added: "There was no fire. We had some incident on our engine, but it is nothing like the fire as you describe."
When asked why the matter had come up this week with an anonymous letter, Taffin said: "You have to ask the guys who sent the letter, because I don't know.
"At Renault we don't have a publication with all the dyno testing that we do every single week, so as it was part of our programme there was no point doing anything on this."
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