Controversial former Formula 1 world champion Jacques Villeneuve has questioned Renault's motive for offering Robert Kubica a number of tests during the summer to examine the possibility of a comeback.

The Polish driver completed two tests in a 2012 car in Valencia and Paul Ricard before moving up to the 2017 car as he participated in the post-Hungarian Grand Prix test in Budapest at the start of August.

Though it was always understood Renault offered the former Grand Prix winner the opportunity to run as an evaluation of his abilities six years after his near-fatal rally crash, that possibility has now been closed following the revelation that Carlos Sainz is to join the French manufacturer from 2018, potentially sooner.

"I honestly don't understand," the Canadian was quoted by F1i.com. "Who ever got a comeback offer after six years?

"At the end of his career, he was struggling against Petrov. He won his race like Maldonado, and what did he achieve after that? Add the fact that he hasn't recovered 100 percent of his ability, and one wonders how he could cope? Or perhaps the cars are just too easy to drive..."

What the tests did prove is the immense popularity Kubica still has with the media covering every angle and Polish fans filling the main grandstand on his test day. The buzz that was created is something Villeneuve believes was the main aim of testing the now 32-year-old all along.

"If he didn't have his problem, he wouldn't get a second chance," he claimed. "That's what shocks me! It's just a public relations thing, and it bothers me because there are many other drivers more worthy but who wouldn't get a second chance. That's hard to bear.

"It's great for him, however, he's lucky."

Finally, Villeneuve would recall his personal experience with Kubica and be highly critical of how the then young up-and comer-handled himself.

"He was our third driver when I was with Sauber BMW and to be honest, he was unbearable back then," he stated. "Socially it was very difficult. For me, it was a very difficult period.

"You know, you have to show respect in the paddock. You must respect what others have achieved in order to respect the environment you work in. So It's difficult for me to imagine anything positive in his F1 comeback."