Kamui Kobayashi has revealed he is not being paid a penny by Caterham for his return to Formula One this season.

Caterham have confirmed Japanese driver Kobayashi and Swedish rookie Marcus Ericsson will form their driver line-up for the year ahead.

Kobayashi returns to F1 after a year on the sidelines following his axe from Sauber at the end of 2012, the 27-year-old instead driving a Ferrari in the GT Pro class of the World Endurance Championship last season.

Kobayashi was offered a new contract by Ferrari for this season, which would have included an expanded role in their F1 programme, such as simulator testing.

But his desire to return to F1 full-time, in conjunction with the fact he offered to drive for free as well as handing over £1million in sponsorship raised by his fans to get him back into the sport, all played a key role in attaining the drive with Leafield-based Caterham.

"It is good they (the fans) are still supporting me. Japanese fans are definitely happy I've managed to get this seat," said Kobayashi.

"The one-year break from F1 was good, driving GT Pro, it was quite a high level of racing which I enjoyed.

"But I am only 27. I still need to race in F1 and that is why I chose to come back.

"Ferrari offered me another contract, and Stefano (Domenicali, team principal) is not happy I didn't take it, but it is my decision.

"I'm taking a risk in my life which is important for me, and Caterham needs different energy.

"So I don't need or care about money. I just want to drive and help the team, to be successful in my life and to bring the team success.

"So I am racing for free, my decision, my approach because I want to do this job. This appeals to Tony, this was my message to Tony, and he is happy about that."

Whilst an obviously agreeable option for Fernandes, the Malaysian entrepreneur insists his decision to hire Kobayashi was more to do with his passion to return to F1.

"Whether I save half a million (pounds), £1million or £2million, in the scheme of things makes no difference when you're talking about an £80million budget," said Fernandes.

"What we thought Kamui would bring is a little bit of a spark, that something you can't really quantify, something that motivates the 250 people (within the team) to say 'we've a chance now, we've a warrior who is going to go in there and do whatever it takes to move this team up'.

"That drives people a little bit more so that's the main reason we have taken him, and we've seen him on the track. It's well documented he goes for it.

"So Kamui was not really a financial consideration, although there are of course benefits as he's from Japan, he's Asian, so there are some business angles for me."