E46 Touring is essentially the same as the E46 sedan, follow the same maintenance recommendations and parts replacement schedule as you would with any 325i Sedan, i.e.
- control arm bushings will go about about 80,000Km
- get the mtce record; make sure oil service, inspection I and II (with fuel filter!) schedule was followed
- look for simple things like the BMW hidden flashlight in the glove compartment, is it there? What kind of tires are on the car? No flashlight or cheap no-name tires indicates the owner may not have cared for the car
- change belts and coolant expansion tank proactively, and thermostat, these are known E46 issues
- VANOS seals replacement after about 120,000km. No low end performance without this.
- test the hell out of the automatic transmission, backup then shift to drive. Stop, quickly reverse, stop, then shift to drive again. Observe delays - I needed transmission custom programmed with codes entered per service bulletin.
- test steptronic, all gears up and down
When choosing the Touring, look for the following important facts, I took months to find the right one (CPO at BMW dealer):
Make sure the rear storage pull cover and cargo screen unit comes with the Touring, it is expensive to buy one later.
Look for full size spare and OEM wheel and tool kit under cargo cover!
Make sure there are two keys and test them, including rear hatch release and panic button test.
Drive a couple - there are a few options such as:
5 speed manual with sport packages versus auto/steptronic
Premium Package - I went with this, HK sound, full power/heated seats, cold weather package, etc
As for mods the list goes on to infinity as to what you can do to customize your ride to match your preferences, the usual starting points:
OEM alarm and custom key programming
upgrade suspension and drop
tinting all around
Custom Tune (e.g. MarkD tune)
Mtech II bumper
M3 strut bar
M3 steering wheel
CF grills, handbrake, shift surround, instrument cluster, etc.
LED lighting, inside and out
clear or smoked corners and sides
Brake rotor or BBK upgrades
etc etc - the sedan parts fit, except suspension, exhaust and LED tail lights, those need Touring part variants.