My personal view. Yes u felt great from because u changing from vios to f30 316. Don't talk about maintenance, wear and tear will damage u quite alot if u worried about the cost. I'm drivin a e60 every services is about 600 plus for just engine oil n oil filter and thats the outside of BMW service center. if u can afford that kind of money and prepare money for wear and tear parts. Steering rack cost about 13k exhaust sensor i think got 4 or 5 sensor cost nearly 6k. U are worry free if that is no problem for u. If not better go for a new car instead. Save more for downpayment for a new bimmer.

6 liters for the n52b25 on 300v.. i forgotten the sensor how much but is not 1.5k the longest sensor is about 1.2k if im not mistaken. this was change about 3 years ago when there is an error on 1 of the sensor.. but i just change it all.

yeah 300 is 1 of the most expensive... sometimes i change to LM. Car was remap, ignition coil change, eisenmen muffler and only drink 97.

sensors are the oem Bosch ones not original BMW. Even the BMW original are made from Bosch. I know the workshop charge more expensive den the normal 1. But he done a great job. Now on Mobil 1 which is alot cheaper.

lol is all depends on the owner. I felt great with 97 especially the Red V. Yours M4 on twin turbos. Even on RON95 i only can smell exhaust fumes laaaa

For NA engines, petrol and Engine oil is very important. If u treat the bimmer well... not much major problem beside the normal wear n tear. For TS if u worry about maintenance cost. Better off with a new car.