Renault on Tuesday reported a 13-percent surge in global sales last year and assured investors it was taking the emissions scandal swirling around it "with the upmost seriousness".
A year and a half after Volkswagen's "dieselgate" erupted, Paris prosecutors are probing Renault over possible "cheating" in diesel emissions.
Sales rose 13.3 percent in 2016 with more than 3.18 million vehicles sold, a record for the group.
The French automaker put its sales success down to buoyant markets in Europe, India and, increasingly, Iran.
"We are making progress in market share in each of our regions," Renault's commercial director Thierry Koskas said.
Renault's former reliance on Europe is decreasing as it sells more vehicles in other parts of the globe, with European sales decreasing from 57.6 percent in 2015 to 56.7 percent last year.
Koskas stressed that Renault would move swiftly to address the concerns expressed by Paris prosecutors about its diesel emissions.
"We are treating this issue with the upmost seriousness and giving it great attention," he said.
Renault cars "respect the law and do not have the 'cheat' software, and so we are completely confident," he said.
Shares in the automaker, which fell last week on the news that a probe had been opened, were up 2.0 percent at 84.87 euros in mid-afternoon trading in Paris.