Ex-McLaren F1 driver Michael Andretti has bolstered the chances of his team proposal being given the green light to enter the series in 2026 after gaining the support of GM sub-brand Cadillac.
But unlike fierce American automotive rival Ford, which has partnered with Red Bull Powertrains predominantly via a commercial relationship, GM covets a major technical presence in F1.
GM motorsport executive director Eric Warren - formerly the conglomerate's NASCAR programme chief - says that this could result in an F1 engine programme, which is under evaluation.
Speaking exclusively to Autosport, Warren said: "GM is motivated to be involved in the car and design, the whole process. It's not white-labelling an engine [a comment possibly aimed at Ford].
"The interaction between Cadillac and Andretti will be throughout the vehicle."
Should the "strong application" submitted to the FIA from Andretti-Cadillac result in an entry for 2026 - with Hitech and Panthera Asia also interested - the squad will run a customer engine in its first season.
Following the creation of a long-term partnership between Andretti and Wayne Taylor Racing, the outfit now has solid ties to Honda, a listed 2026 power unit manufacturer, via the Acura brand.
However, with Red Bull now developing its own F1 engine, there are doubts about the Japanese firm's topflight future, which would leave Renault as the most credible supply route for Andretti.
But GM will consider its own engine programme for as soon as the 2027 campaign, with Warren explaining: "Looking beyond 2026, our view is that we want to get racing and making sure we are competitive and then look in 2026 at what makes the most sense.
"We could, of course [when asked if GM would construct its own engine].
"We can't by rule because the 2026 power unit manufacturers have been declared, so we would be looking at the earliest in '27.
He added: "It is something we are looking at. We are looking at power units. Andretti has a power unit partner with which we can get racing quickly."
Cadillac already constructs the 5.5-litre naturally aspirated V8 for its LMDh prototype via the GM Performance and Racing Center in Pontiac in Michigan.
Asked if an F1 engine would also be done in-house, Warren said: "I think it is difficult for a manufacturer to say an engine is 100% in-house. They always have technical partners they work with. But I think we have capabilities that would be substantial to that.
"I think we could do that, whether we chose to and what elements, has yet to be determined."
The 2026 engine regulations have notably ditched the expensive and complex Motor Generator Unit – Heat, which has paved the way for Volkswagen Group member Audi to enter via a works engine programme and a majority investment in the Sauber team.
