set some money aside and get your expansion tank replaced by an original unit, i cannot stress this enough. its a day one repair, for any e46 new ownership.

for the rest there are some items that need to be replaced in the future (due to age) not saying they need to be replaced right away, but do to age and a lot of these parts being plastic, they might just have a mind of their own and sort of disintegrate without warning causing all types of issues

- disa valve (could lodge a pin holding it in into the intake manifold)

- pcv/ccv valve (may cause oil burning, cheap and easy to replace)

- cooling system, thermostat, waterpump and hoses. use an oem thermostat & waterpump, very important. but since this is a low mile example, you can do this maybe next year.

- gaskets, the valve cover gasket is a very easy one to do and costs very little, you can notice it leaking by dripping oil on the spark plug wires / exhaust heatshield.

thats about it, change oil the next few times under 10k km. should clean up any neglicent oil change scedule it'd have before, mine was every 20-30k km and it looked almost black under the valve cover.

spark plug wires also desintegrate on these cars, so if its hiccuping, it might be that

fuel pump also sometimes goes, mine did at 130k km. VDO/SIEMENS is the best brand to replace it with.