Dang, IDK how this happened, but it looks like I never started a build thread for this car. perhaps (1) i knew it wouldn't be a build so much as just a "maintain until time to discard", or (2) because i didn't expect to keep it this long. either way, she's been in the fleet for over 4 years and 72k miles, so i'll go ahead and bore you with a summary of our relationship. i'll add detail to some of these items in subsequent posts.
Since Sept of 2015 (update: in June 2019 i picked up a 2001 Sonoma and the E60 became AngryKid#1's daily), i have DD'd a 2007 525xi, automatic, non-sport. the 525 is the least powerful N52 fitted to these cars, and the "x" in xi indicates AWD. bought with 136k miles on it. currently showing 209k miles. reliability IMO has been no worse than i'd expect from any car within that range of age and mileage.
the PO was not a car whisperer by any stretch, so it came with some deferred maintenance issues, which i addressed at my leisure. here's a list of things i've addressed in the last 4 years that are not what i'd consider routine maintenance, although some are probably routine for BMW:
2016-01-30, 143k: replaced original (electric) water pump and thermostat, replaced gaskets on oil filter housing and oil cooler. water pump R&R is a motherberkeleyer due to packaging with AWD. there's an automated coolant bleed procedure that must be run to get air pockets out of coolant passages in cylinder head.
2016-09-22, 154k: replaced accessory drive belt and idler/tensioner because they were getting noisy. also replaced both front suspension "tension strut" bushings and both outer tie rod ends.
2017-06-02, 165k: replaced both front swaybar end links
2017-08-26, 168k: replaced transmission mechatronics sealing sleeve, changed ATF and filter (which is an integral part of the pan, so instead of a $20 filter and a $20 gasket, it's a $130 pan kit). also drained and replaced transfer case fluid. all of these items were on the dealer PPI i got at 136k. Ignored internet-conventional wisdom regarding changing ATF. 40k later, trans is still performing flawlessly.
2017-10-12, 170k: replaced heater control valve that was booger-berkeleyed by Blue Devil stop-leak, and flushed/filled coolant with BMW long-life coolant.
2018-01-28, 175k: cleaned VANOS solenoids and replaced associated o-rings.
2018-02-23, 176k: repaired broken wires in trunk lid harness. cold-work / fatigue failures where the harness has to bend when the trunk is opened and closed. poor routing caused this failure.
2018-04-04, 180k: replaced original alternator, also replaced (again) gaskets on oil filter housing and oil cooler. also replaced valve cover gasket/seals and ran ValveTronic relearn procedure.
2018-07-02, 184k: replaced original starter, replaced one crumbly CCV hose i broke while removing intake manifold to access starter. i later learned that starter R&R could be done without disconnecting this hose.
2018-07-07, 185k: replaced original transmission cooler thermostat, cleaned blockage due to jellified Blue Devil stop-leak from radiator and trans cooler, replaced coolant with BMW long-life coolant.
2018-08-09, 187k: replaced VANOS filters aka "non-return valves" which are located in the passenger side of the cylinder head, not on the front of the head with the VANOS solenoids. also cleaned and tested VANOS solenoids, and replaced all 6 COP ignition coils. Also fixed TPM Malfunction by soldering a jumper wire into the TPM PCB to bypass a broken pin in the connector. Pin was corroded, with no evidence of moisture anywhere. poor material selection? poor interface fit between terminals on PCB and terminals in harness-side connector? IDK.
2018-12-28, 194k: Dealer executed NHTSA recall 17V683 to replace heated PCV valve due to electrical short melting the PCV and some nearby components.
2019-02-17, 197k: replaced (again) oil cooler gasket.
and there's been a couple of ghosts in the machine: the first ghost is in the HVAC system. twice in the first year, the HVAC fan stayed on when i shut the car off. i had to pull fuses to get it to shut down. could not repeat. hasn't happened again.
the second ghost is in the clockspring assembly. occasionally, especially in sub-freezing ambient temps, the SWA sensor loses calibration and disables VSC, so it throws a DSC + 4WD fault. this is cleared by cycling the key and turning the steering wheel full left - full right - back to center before driving off. it happened 1x in 2016, 3x-ish in 2017, 3-ish again in 2018, and about 20x in 2019. interweb says clockspring can be disassembled and cleaned.