McLaren announced on Friday that it would extend its current deal with Mercedes for five more seasons, from 2026 until 2030.
It means McLaren is one of the last teams to commit to an engine manufacturer, with fellow Mercedes partner Williams now the only remaining team to sign up for 2026's rules shift and beyond.
Stella explained that staying with Mercedes was an easy decision because of the continuity it provides and the reassurances it received from Mercedes High Performance Powertrains in Brixworth about how well its 2026 power unit is progressing.
"It was quite straightforward because we are very happy with the ongoing collaboration," Stella said. "They were absolutely instrumental, even in the progress of the team this year, I have to say.
"But above all, the kind of reassurance we got from a technical point of view, the operational standards, just how solid is what we saw, when we checked what was at stake for 2026, made this decision quite simple for us.
"So, we are just delighted that we have this level of continuity and stability as we look forward."
Source: Autosport