Fernando Alonso has apparently turned his back on data being produced by Renault's pre-season simulations and refused to contemplate challenging the Formula One frontrunners until the R28 hits the track.

According to claims in Spain's as.com, windtunnel data suggests that the new Renault could be as much as 1.6secs faster per lap than its predecessor, but Alonso appears not to be putting his trust in figures and wants to wait until the car performs 'in the flesh'.

Despite claiming to have opted for a return to Renault because 'that was the option that presented the most optimistic perspectives for 2008', the double world champion refuses to countenance a chance to challenge the likes of 2007 nemeses Lewis Hamilton and Kimi Raikkonen - at McLaren and Ferrari respectively - even though the R28 appears to be producing some remarkable advances.

While the regie may also benefit from the loss of traction control electronics by being able to shift its traditional weight distribution to better effect for tyre life, Alonso wants to wait until all the major contenders hit the track together before making any great predictions about his season. The Asturian is unlikely to get his chance to try the R28 until the third week of January, while Ferrari, McLaren and BMW - the teams that, on the road at least, finished ahead of Renault - could all hit the track before that.

The Scuderia's launch was recently announced for the 6 January, while BMW had earlier earmarked the 14th. Renault is not due to officially unveil the R28 until the very end of the month, but recent seasons have shown that the team is prepared to track test its machines before they appear in full livery. McLaren has yet to announce a launch date, but will not want to waste time getting its challenger on track.

One thing that Alonso will be counting on is Renault's near legendary reliability record, especially with long-life gearboxes set to join similarly restricted engines on the team's watch list. Although pre-season miscalculations and a rushed R27 hindered the regie's double title defence in 2007, the team has revealed that it has been hard at work on the R28 since mid-season, and should be better prepared for the battle to regain ground lost this year.