Formula One's switch to a standard electronic control unit has given McLaren a head start as makers of the system, Renault engine head Rob White said on Wednesday.
McLaren and Microsoft won the contract to supply all teams, a development which allowed the governing International Automobile Federation (FIA) to ban so-called electronic 'driver aids' such as traction control this season.
"Everything is different for us," White told reporters at the Jerez test circuit. "The control system is different, all of the tools are different, the environment in which the engineers work is different.
"It has taken a huge amount of time and effort simply to understand the things that are different.
"Clearly the kit is the same for everybody and the potential is the same for everybody. But those people that start further away have got a longer road to travel to get to their optimum," he added.
"It's clear that McLaren were closer than other people to the system that we have in 2008. They haven't had to do the work necessary to adapt to this new system."
Red Bull technical head Adrian Newey, who was at McLaren before joining his current Renault-powered team, agreed.
"Renault has used a lot of effort simply trying to get their engine to run properly on the new ECU, and of course as soon as you do that you are not putting the effort elsewhere," he said at the launch of the new RB4 car.
"So it has been a slight disadvantage. I guess it has been the same for everybody except Mercedes (McLaren's engine partners)".
Outgoing Ferrari boss Jean Todt said earlier this month that McLaren would enjoy an early advantage and his championship-winning team would have preferred the unit had been made by another company.
McLaren boss Ron Dennis said at his team's car launch last week that all manufacturers had been given the opportunity to tender for the contract.