In an effort to address specific noise concerns, BMW in the United States updated the turbocharged engine software on 335i/xi and 535i/xi models built from June 2006 through March 2008. However, the updated software caused a small amount of increased turbocharger lag under certain circumstances, which BMW confirmed is noticeable and now plans to address by releasing a new update.

Release of the new software to restore the original turbocharger response is planned for January 2009, and it will be available for vehicles produced from September 2007 through March 2008 when they are brought to an authorized BMW center for a repair that requires a programming update.

Owners with vehicles produced from June 2006 through September 2007 may also request installation of the January 2009 software update. However, BMW states that changing to new software may increase engine noise levels under certain circumstances.

Other vehicles that use the same N54 3.0L twin-turbo six, such as the X6, 135i, as well as 3-series and 5-series models produced from March onwards are not affected. Earlier this year, a global panel of judges awarded the 300hp N54 as engine of the year, picking it for its flexibility and mix of performance and fuel-economy.