Supplying power units to its works teams and three customers teams this season, has not been without its problems for Mercedes, as engine boss admits to "some issues".
Other than its own (multi) championship winning team, and customers Aston Martin and Williams, this season sees Mercedes re-partner with McLaren.
While most believe the German team is heading for its eight successive brace of titles, many want to see it face a serious, consistent challenge.
Whether it is the German outfit reverting to its customary underdog stance or whether there really is glimmer of hope for its rivals remains to be seen, but as the launch season gets underway, engine boss, Hywel Thomas admits that the 2021 engine has encountered some early issues.
"In terms of readiness, we've got plenty of engines in build at the moment getting ready for the new season," says Thomas in a pre-season video by Mercedes. "We have already got some of them together and we have also got engines running on the dynos right now, doing their durability runs.
"There are also engines for our customers too," he adds, "which are already with them and either in the back of their chassis and fired up, or in the process of doing so.
"We have got some issues with the power units," he admits, "we know we have issues but we have plenty of plans in place to fix all of those issues. I'm sure it will all be ready for the first race."
In addition to those unspecified issues, Mercedes, like its rival manufacturers, has to contend with the fact that only upgrade allowed over the course of the season - not to mention the subsequent freeze - has had to alter its approach.
"It's the first winter where we have prepared for only one single upgrade for the whole season," he said. "So, we have to get all of our performance into the first power unit that goes to the first race, whereas in previous seasons we have been able to split that up into different packages for each power unit that gets introduced.
"So, with that challenge, we have to get absolutely everything there for the first race and make sure it's completely reliable.
"Also, there are more races this season and the same number of power units, which means that each individual power unit needs to run across more races. We just have to make sure that we are ready for that and focus even more on reliability.
"We also have the challenge of a pretty short winter, as we didn't finish racing until the middle of December and now, we're straight back into it. So, if anything, we've had more to do and less time to do it in."
Of course, having won 103 (74%) of the 138 Grands Prix held since the introduction of the hybrid formula in 2014, whatever the issues or reliability concerns, Mercedes remains the hot favourite.