Former Formula One champion Damon Hill says Daniel Ricciardo made the right call to leave Red Bull and ensure he wasn't "marginalised" but has questioned whether Renault will ultimately deliver the speed machine he needs to rule the world.

Ricciardo heads into the Australian Grand Prix on Sunday again a focus of attention but for different reasons than in previous years. Where this time last year debate swirled as to whether he would remain with Red Bull, or whether he could make the podium in Melbourne, this year it's primarily about whether Renault can make progress towards its stated aim of producing a car by 2021 that can contend for the title.

While fellow Australian and former driver Mark Webber has said Ricciardo's decision to switch teams was "weird", Hill said he could understand why he left, coming at a time when Red Bull had officially, or unofficially, anointed Dutchman Max Verstappen as their No. 1 driver.

Daniel Ricciardo in his new Renault. Credit:AP

"I think he has lots of self belief. He is one of the loveliest characters in the sport. He is a ray of sunshine. A lot of drivers go around with a big glum face. He always has a massive grin on but deep down there is a burning desire to win and he knows that his clock is running," Hill said.