Lotus Renault technical director James Allison has admitted that the Formula 1 team have not been able to provide two equal configuration cars so far this season.

Allison said that because of this Finnish driver Kimi Raikkonen has been provided with new upgrades before his French teammate Romain Grosjean.

"[Grosjean's] not had an easy weekend either here [in Malaysia] or [in Australia], because we haven't been able to provide two cars in exactly the same configuration on either occasions," Reuters quotes Allison as saying.

"In Melbourne on Friday he was running a step behind Kimi in terms of his aero package, and then he had the upgrade for Saturday morning but then Saturday was disturbed by the weather. Here, once again, we only have one set of [new] kit and we've chosen to run that with Kimi and Romain is disadvantaged for that.

"You try to upgrade the cars as fast as you can and generally speaking, that means that you're always going to have one set of kit ahead of the second set and that almost inevitably means that one driver gets to try it before there is a second one available."

Raikkonen won the Australian Grand Prix and was fastest in the second practice session in Sepang.