Returning Formula One champion and Lotus star Kimi R�ikk�nen has warmed up for the start of winter testing with a track run in Valencia – but the Finn's success will depend on exactly how good Lotus' 2012 car is, according to F1 legend Niki Lauda.

R�ikk�nen, champion in 2007, completed a two-day test at Circuito Ricardo Tormo in Valencia this week in Renault's 2010 chassis with the aim of acclimatising to the category.

The Finn has spent two years away from Formula One, but this week completed 171 laps over the two days, a total of 413 miles and the equivalent of more than two grands prix.

'Overall the two days have been helping me a lot,' said R�ikk�nen, who will drive for the Hethel-backed team in 2012.

'Even though I was using a two-year-old car and the Pirelli demonstration tires, I learned about working with the team and the engineers, and which things I can focus on the new car once we get to Jerez for the first test.

'It was great to be driving an F1 car again and from that aspect I feel very positive. Overall the two days have helped me a lot.'

Alan Permane, Lotus F1's trackside operations engineer added: 'Kimi's pace improved from yesterday as we would expect and we completed several start, pit-stop and clutch simulations. Overall it as been a productive and valuable two days.'

Winter testing officially starts in Jerez on February 7, before the season gets under way in Australia the following month.

Triple world champion Lauda is excited by R�ikk�nen's return: 'It's excellent news that Kimi will be back,' he told Autosport.

'He is an exceptional personality and will create huge interest and excitement with media and fans.

'It is a good move for Renault – or Lotus as the team is called now. It depends on how good the car will be, because Kimi will only shine in an excellent car.'

Following four days at Jerez the F1 paddock twice travels to Barcelona ahead of the curtain-raiser in Melbourne. Mugello will also host three days in May after the FIA brought back midseason testing from 2012.