Referring back to DaveA’s and sootchucker’s points amongst others, the value drops are common to all of the segment now. My TCR books at sub £26k at 15 months old and would have retailed at a whisker under £40k with options. I reckon in part ex I’d be lucky to see £25k.
These things drop like stones for a year or two which makes buying new a mugs game unless you’re pretty wealthy, have a decent company car scheme or plan keeping the car for 4 years plus.
For the purpose of this thread as you can’t do a GTI PCP quote right now I just did a 135i finance quote.
24 months on a car specced to a fag paper under £40k (our new favourite cut off point when it doesn’t see like a couple years ago we were aghast at spending over £30k on a Golf sized car) and the GFV is just over £20k using 8k miles PA.
A £20k drop.
But the industry doesn’t want us to look at figures in that way anymore, they just want to know “how much an you afford a month”
Hell, you could buy a second hand pre-facelift R, stage 2 it, blow the engine showing off to your mates and still have spent less than £20k after rebuilding it!! The latter would probably be much more fun but I’m old and have no mates so...

As for the M135i itself, I remember posting up about my test drive in a launch demo car last year and saying how Golf like like it felt but also how refined it felt compared to my Ed40 (non DCC on both), but to be honest I reckon a 7.5R wouldn’t be that far off the BMW in refinement, but I can’t say for sure.
The GTI doesn’t have the prop-shaft to stiffen the shell and has very thin panels which transmit certain noises unlike previous generation Golfs (mk1 and mk3 aside) and I wonder if the FWD 1 series is as refined at the strut brace equipped M135i.
To me a Golf GTI is incredibly refined for the type of car it is but there are certain irregularities it just can’t cope with. Maybe more factory development time on the Milton Keynes roads near VW UK HQ would be a good thing instead of endless laps around the Nurburgring trying to shave a few tenths of seconds per lap. Still, it’s a nice job for someone!