M235i Coolant overflow pipe ends are prone to snap. Some people (incl. me) replace them at ~40K miles as it’s an easy and relatively cheap thing to do. If the car’s in the workshop anyway, then worth asking the garage for a quote to replace as pre-emptive maintenance. There are also some DIY threads on the forum, if I recall:
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Also the notorious turbo charge pipe - at least do a visual inspection to check it’s not cracked. BMW do a replacement part that’s now beefed-up as a result, but never admitted it was a fundamentally flawed component on the original cars. Thee are metal replacements available but the job is relatively difficult given where the charge pipe is, so it’s a pricey pre-emptive option. My 2016 M235i convertible is at 55K miles and I’m currently pondering the cost/risk of this as it’s around £1K to get it replaced by my independent specialist.
My BMW Extended Warranty fine print specifically excludes all water coolant hoses. This implies that they’re more likely to go with age than other components (which is no surprise). So worth checking closely.
Also consider Extended Warranty. It might not be economic for you but mine covers everything other than the water hoses. I’ve claimed on it once (about $5K of labour and parts) so I’m obviously a fan, but like all insurance you have to do the probability-cost equation for yourself. I gather the cost start to ramp up a lot over 60K miles.