Speaking to Speedcafe.com during his visit to the weekend's Perth Super Sprint, the racing legend ruled out a move to a third entry.
Reports of a potential expansion had emerged in recent weeks amid talk of the squad's apparent interest in Garry Rogers Motorsport star Scott McLaughlin.
“It's not on the cards for us,” Penske told Speedcafe.com of a third car for 2017.
“Two cars is what we're going to run for sure.
“We've got work to do before we start thinking that we're going to run three cars.
“If it's a 100 yard football field we're on the 40 yard line. We haven't got to midfield yet.
“We need to stay with the guys we have, make a difference and get better.”
The retention of a two-car model will seemingly pit Pye and McLaughlin against each other for the second seat, should the latter wish to move from GRM.
Despite ongoing suggestions that McLaughlin is already destined for the drive, Penske stressed the team's position that it will wait until later in the year before making a call.
The team played a similar card last year with Coulthard, waiting until October before striking a formal deal with the Kiwi following months of speculation that he had the drive.
“We've had a number of drivers come to us, but we have two good drivers right now,” said Penske.
“Probably no one wanted to drive for us a year ago, so it's interesting, but we need to take the talent we have now.
“I think we have got to give Pye a chance to show what he can do.”
While Coulthard was a big name recruit over the off-season, a carefully spoken Penske outlined his preference for growing talent in-house within his teams when possible.
“I think the two of them work well together,” he said of his current combination.
“They're experienced, they're young, they've got long-term (potential).
“Maybe they're not regarded as the top guys at the top level but that's what I want because I know they can get there.
“The goal is to build them so that they can get to the top like we've done with (Brad) Keselowski, with (Joey) Logano, with (Rick) Mears.
“We do better taking these drivers and growing with them and I think that's what we want to do.”