There is obviously a difference in quality between the works team engine (at Mercedes, Red Bull and Ferrari) and the customer engines.
For example:
- Mercedes started the season with an extra power qualifying mode on their engine that FI and Williams didn't get until a few races into the season.
- Likewise RB and STR are getting engine updates much faster than Caterham are.
- Ferrari has even started getting Marussia to test experimental parts on their engines.
The current regulations leave customer teams (the vast majority of the grid), no choice but to accept this situation. If they are lucky like McLaren they will pick up a works deal.
Mercedes mechanical failures are hardly statistically significant to the discussion, especially considering they are overwhelmingly a mechanical problem relating to the braking system.
Ofcourse works teams always have an edge because they can better design the whole car around the PU. But they also currently have the added advantage of receiving new engine developments at earlier races than the customer teams.
Surely if F1 is to maintain decent size grids there needs to be safe guards in place to protect midfield and backmarker teams in instances like this?
I don't know whether that is true or not, but it sounds like it would not be with the homologation and all. I can't dispute the engine modes, but I would guess that customer teams are capable of running their engines at full power, which is all a super special quali mode would have to be - if you're telling me customer teams have to wait an arbitrary amount of races until they can use 100% engine power, well, it doesn't sound logical, and if something isn't logical it's usually not true. Although in F1 there are certainly exceptions. If this was the case though, I'd expect Mercedes to be fastest in every speed trap, and they simply aren't, I really don't see any hinderance.
As for the 'updates', like I said...the homologation takes care of that, no teams are just bolting updates to their engines willy nilly and seeing how they go. Finally, Mercedes' mechanical failures are fairly relevent, actually. They have had many power issues, not just relating to the braking system. Not all of them have caused retirements, but an issue is an issue nonetheless. Again, if there was a substantial difference in quality, the customer teams would be having more issues, not less.