Former Toro Rosso driver Jean-Eric Vergne admits he "laughed" upon hearing that Brendon Hartley had returned to Formula 1 with the junior Red Bull team.

The New Zealander was brought back to replace Carlos Sainz from the US Grand Prix last year and did enough to maintain his seat with the Italian team for 2018, albeit finishing last of the 15 cars to reach the checkered flag last weekend in Australia.

Many had touted the Frenchman, who competed with Toro Rosso from 2012-2014, as another alternative but it was Hartley's performances in the WEC with Porsche which earned him a second chance.

"It makes me laugh that Red Bull called on Hartley given that he's the one they fired to give me his seat in World Series by Renault," Vergne was quoted by F1i.com. "I find this rather amusing!"

After seeing his F1 dream end by the arrival of Max Verstappen, Vergne had a stint with Ferrari but has since found his calling in Formula E, where he leads the Season 4 championship with Techeetah.

"Looking back, I could have handled things differently," he admitted. "I went through a hard 12 months, looking at how I could turn things around.

"I changed a lot of things in the way I approach the sport and I was able to learn from everything that happened.

"Today I don't believe that I can be hurt in Formula E the way I was hurt in F1," he added. "Outside the car I can now see everything with a different eye. As a global driver that's much better."

Though some in F1 have mocked the all-electric series, Vergne credits the opportunity to compete as the "turning point" for his career.

"I was lucky to join Formula E at the right time," he said. "I quickly changed my mentality and my state of mind. Today, I think it's the best thing that can happen to me.

"I think it was the turning point of my career. In any difficult or negative situation, there are positives to draw. You just need to extract them."