Even for £30k id rather the golf, the depreciation on the BMW will be horriffic it always is, the quality of everything lacks in the BMW IMO and the golf will be a much better place to sit. No brainer even with a little less power, take it for a stage 1 and you'll be laughing! 
Nothing you just said makes sence.
Does to me 
The moral of the story is, i would have the Golf 
You clearly are quite silly. If you want the Golf, that's fine - don't try and justify it to yourself with fantasy logic though, that makes you look stupid.
The M135i has won pretty much every magazine's Car of the Year, they heaped praise on it's drive, its spec and its build quality... at a £30k price point, it isn't Bentley quality, because it isn't Bentley priced. I've been in a MK7, that also has a similar £30k interior.
The GFV on my M135i's 3 year PCP is 55%. That will be the absolute minimum I get for the car, I'll possibly achieve more selling private. If they're going for less on the open market, then fair enough... but I'd not expect BMW to be punting high without a good reason why, everyone had their fingers burnt with that when PCPs were invented.
Incidentally I had a 135i coupe prior to this. I sold that at 5 years old for 40% of its invoice.
Example of 3 year old 135i - still £20k+, and roughly 60-65% of invoice at retail prices.
http://www.pistonheads.com/classifieds/used-cars/bmw/1-series/bmw-1-series-135i/1287334 http://www.pistonheads.com/classifieds/used-cars/bmw/1-series/bmw-135i-m-sport-coupe-2010--super-big-spec-example/1262907 Now tell me again how their depreciation is horrific??
