However, Jay Penske clearly remains hopeful that Chevrolet will be able to supply an additional engine lease later in the year, and has opted to retain all the personnel from the existing #6 and #7 car teams and not to streamline the operation into a one-team set-up for the time being.
Penske confirmed to the Indianapolis Star
on Wednesday that the one-car line-up would be in place for at least the next two months while he worked on getting the additional lease.
The news means that the field will now consist of 25 regular entries for the foreseeable future, with 13 powered by Chevrolet and 11 with Honda engines, leaving HVM's Simona de Silvestro the sole Lotus representative.
Rahal Letterman Lanigan Racing had hoped to run a second car for 2011 GP2 Series runner-up Luca Filippi, but still faces problems with the Italian's financial backing together with the lack of an available Honda engine after team owner Bobby Rahal passed on his original lease option to Sarah Fisher Hartman Racing just before the first race of the 2012 season at St Petersburg.