There is much more to a car besides normal services. You need to do much more research.
My apologies if I sound rude but you not making use of any advice given and that will get you right back to your current situation only it will cost you much more.
No stress man you not rude.
Its not my 1st car nor will it be my 1st BMW.
I have had loads of BMW's its just the 320d from hell e90 also 1st diesel ever which i had to learn allot about which has given me the most problems.
All of the other petrol BMW's i repaired and maintained myself, with the diesel hitting me hard with school fees.
And from my experience over the years things are not that expensive if you do it yourself.
Its like people don't own toolboxes anymore and they afraid to pick up a spanner, then fork out ludicrous amounts of money to a workshop that uses apprentices on minimum wage to do general maintenance on your car learning as they go ... ;p
Then want to say oh this car is so expensive to own as some sort of bragging right rather settle for X or Y
For instance a rebuild of the Z3 2.8l engine was quoted 45+k a few years ago. Did it myself with parts purchased from alert autospares for less than half and that car is still running problem free to this day.
I get things break, i get that there's not one car on this planet that doesn't break. But saying a cars maintenance costs (not repairs if something breaks) is higher than another model using the same chassis same electronics same drivetrain and same maintenance schedule simply because it has a different engine, i don't agree with. I can agree that repair costs if something breaks and its a problematic engine that it can get very expensive.
But from all the forums discussions writeups reviews, articles etc. the consensus is that the N55 is very reliable, common issues boils down to leaky oil filter housing gaskets, flimsy charge pipes, and leaky valve cover gaskets.
So you put in a aluminum or stainless charge pipe, any engineering shop can make one if they have a pipe bender, bead roller and a welder. Dont need to buy a brand name one costing 10 times as much. And a tube of good quality RTV + new seals / gaskets and a good clean before install sorts out the rest of its common issues.
As for maintenance, 10l of 0W30 oil is going to cost the same whether it goes into a lawnmower a snowmobile a tractor a n55 or n47 same goes for all other fluids like coolant, diff oil, gearbox oil, brake fluid etc, oil filters / fuel filters might be slightly different in price but not 1000's, cabin filters identical, brake pads and rotor a few 100 buks different. So where is this huge disparity in cost of maintenance and servicing.
Both 320d and 335i have the same suspension only differing shocks and spring rates, depending on if its a sport or not.
And when i ask the question of how maintenance cost differs none actually answer the question with nothing more than a snarky reply to the tune of 'you know nothing Jhon Snow" š¤£
So if its advice that is valid, like the warning on the N20 models, i do take the advice, because its based on well documented facts which can be easily found if someone informs you about it. Like hey lookout for the N20 they are generally not reliable and hit and miss. Thanx man let me go look it up, sure enough what they say rings true.
But saying, oh that model is expensive and requires loads of maintenance, and all searches shows the exact opposite ... then i tend to question it.
But unfortunately advice given from someone who does not know which side of a rachet wrench to hold and does all repairs with his checkbook I tend to steer clear from because repair shops see them coming a mile off.
No offence to anyone its just my perspective on things.