Ralf Schumacher has expressed doubts about the suitability of Indycar drivers for Formula 1 as Cadillac prepares to enter the grid in 2026.

Mario Andretti, team advisor for Cadillac F1, recently named Colton Herta, who currently drives for his son Michael's Indycar team, as "definitely" a strong contender for one of the new team's race seats.

"From our standpoint, I think the play at the beginning would be to have one experienced driver—nationality doesn't matter—and then a young American talent," 1978 world champion Mario Andretti told NBC News.

While Schumacher agrees that Cadillac should aim to include American drivers in its lineup, he questioned the readiness of Indycar drivers for F1.

"On the other hand, the Indycar level is not the same as the Formula 1 level," Schumacher told Sky Deutschland. "We've seen that on numerous occasions when they test.

"But maybe there is some super-talent lurking over there that no one has found yet," the former F1 driver added.

Schumacher, uncle of former Haas driver Mick Schumacher, suggested that Cadillac would be better served by prioritizing a proven driver to help guide the team through its debut.

"I assume that they will get a proven element in the car to give them a starting point," Schumacher said. "They're starting from scratch with everything, and that is extremely difficult.

"That's why in that case you have to have someone who you know can do it and who you can rely on."

Apart from the driver lineup, Schumacher expressed confidence in Cadillac's ability to succeed in Formula 1, despite the challenges of entering the sport as a new team.

"It will of course take some time before GM comes on board as an engine manufacturer, although it's a huge corporation, and whatever they tackle will work in the end," Schumacher said.

Schumacher also highlighted the significance of Cadillac's entry for Formula 1.

"All of this is important for Formula 1 because it sends a strong signal when such a global player wants to get into the premier class of racing," he said.

"Formula 1 is continuing to grow. I'm looking forward to there being eleven teams, because that means two more places for young drivers. We know how difficult it is at the moment with only 20 cars.

"In 2026, we will have ten percent more seats available," Schumacher concluded.