Sorry but, it DID happen. I won't post a link because I'm not sure if I can, but if you read Autosport forums about MP4-30 you'll find that someone called Clrnc posted an interview as he heard it in FOX featurette. This is what he wrote on may the 16:
There's a feature on Fox with Mukumoto on the latest development of the Mclaren Honda. I briefly caught a glimpse of it just now. When it's available on demand I will post some of the excerpts here.
Q: Hi Ryo, nice to meet you here. Could you tell us the latest development of Honda?
RM: Hi. Currently we are no near top. We are developing still, but it's no easy. We have good (progress), about half (50%) and we continue to fight. We have good onwards from the engine, but right now we are still too far.
Q: Alright, what's the problem with the engine these few races?
RM: We cannot run full like others. Our engineers good work in Japan and we have manage to reach getting 70% full power in supeingo (Spain), and we will try to extract more from power engine. The way our engine designed mean's it's all new and we cannot examples from the rest, we have to experiment ourselves. The position of various key components are unique and some are not ideal, but some good. We did alot of research before coming up with this design, I admit some have not worked but we change them soon use tokens and they will good.
Q: Could you see Mclaren-Honda winning a race this season?
RM: No, difficult next season too. You know new team hard to win race, compare to the rest who work long together. We will try to win a race next year, but no guarantees in motor. Our target is to be near 3rd team (Williams) at the end of this season. It would be a good (achievement) if we do it.
Q: We have heard a lot of things about the Mclaren chassis and the size zero rear end. Care to share more about it?
RM: Eh... small size good for aero, and we package our power (engine) to match it. There is more to (extract) it, but currently if you notice we have not make big steps in aero. There is a big change coming up (b-spec), on target for England (Silverstone). It will be launched with our new engine.
And this is from where I suppose Marca wrote the news. 05/17/2015.