Italy's Autosprint is reporting that Mark Webber's car only narrowly passed post-race scrutineering at Valencia after officials "examined carefully" the new rear suspension layout.
Allied with the innovative 'double floor' which was also debuted last weekend, the developments helped Sebastian Vettel to set pole and dominate the Spanish street race until his retirement.
When asked about his new dominance, the German driver admitted: "That was surprising even for us. We did not expect to pull out 20 seconds over 20 laps.
"Until the safety car I had an extra pitstop in my pocket, which this year is extremely unusual given how close together the field has been," he told Auto Motor und Sport.
"It certainly would have been a good result."
Vettel admitted the latest developments were a big step forward for the RB8 at Valencia.
"Yes and not only in a certain area, we simply have found more grip everywhere and have found a positive impact for the wear of the tyres," he said.