I'm not denying that Peugeot has also improved as the survey shows but I don't agree that they turned themselves around years before Vauxhall did, I feel the opposite has happened.
The opposite cannot have happened without Peugeot getting worse. And it's fairly easy to pinpoint when Peugeot's fortunes began to improve, though I probably did it a disservice by saying five years ago, as it was around the time the RCZ came out - a demonstrably good car and one of surprising quality, and one that arrived in 2009 - so eight years ago.
Vauxhall has undoubtedly improved in recent years, but having driven a large number of both the current Vauxhall and Peugeot ranges it's hard to pick an example where the Vauxhall is better than the equivalent Peugeot.
Possibly the Insignia vs the 508, though given both are in a pretty mediocre class as it is (and all are a fair way behind the Mazda 6) that's hardly an accolade worth celebrating. The new Astra is better than the old one, but not as good as the 308, and when it comes to the stuff those of us on GTP might care about, Vauxhall's hot hatches aren't a patch on Peugeot's offerings.
Peugeot/Citroen may have recently improved but for much longer than Vauxhall has, and possibly longer than GM Europe has even existed, the quality has been lacking.
That's a rather difficult thing to quantify, not least because GM (Europe or otherwise) is hardly a standard-bearer for quality. There have certainly been some badly-built Peugeots, but then there have been some badly-built Vauxhalls too, so it's swings and roundabouts. I'm not sure it's of particular relevance since again, recent evidence suggests otherwise on both counts.
That's a hard historic reputation to shake hence my point some of the poorest constructed cars in Europe.
Whether you're able to personally shake that reputation or not doesn't alter the evidence, which you yourself linked to! And that evidence directly contradicts your opening statement.
I'm stabbing wildly in the dark here, but could it be that you simply don't like Peugeots very much and quite like Vauxhalls, so are a bit miffed that the former might take over the latter?
I also don't agree that Vauxhall has gone from terrible to mediocre whereas Peugeot has gone from, less say mediocre, to good.
And you are welcome to disagree, but that doesn't make it correct.
More accurately, I'd say that over the past few decades Peugeot has gone from very good, to pretty poor, to very good again, while Vauxhall has gone from atrocious, to mediocre, to marginally less mediocre.
Peugeot still doesn't have the engineering polish of Vauxhall
A phrase not exactly packed with meaning, unless you're referring to something like, I dunno, the operation of indicator switches, which I will concede Vauxhall does quite nicely. If we're talking say, engines, then the recent Peugeot lumps I've used have blown the Vauxhall ones out of the water.
I do quite like Vauxhall's new twin-turbo 1.6 diesel, but I'm not sure I could ever hand-on-heart recommend anyone buys a 1.6-litre diesel anything, as I'm not that cruel.
In my opinion Vauxhall could make better strides forward in the care of someone else whereas PSA will probably hold them where they are.
And again, you're welcome to your opinion, though I do wonder what exactly it might be based on.