Everything on the engine of the E46 is plastic. Manifold, valve cover, thermostat housing (electronically controlled thermostat), DISA valve (look it up, loads of fun), coolant hose connections etc. Plastic as far as the eye can see. They all age, warp, crack and need to be replaced every few years. If you like to DIY, you're going to hate the E46. Every nut and bolt on the engine, transmission and suspension is 2 sizes too small. Don't even think of doing any work on it without torque specs and torque wrench. Even then you'll still break bolts just trying to remove an item. Keep the broken bolt extractor kit handy. I don't like these cars because they are fragile. Even MBs from the crap era (96-05?) like M112 and M113 powered W203s and W211s are far more rebust and user friendly. This is coming from experience on 2 E46s and 1 E39.

Oh and one more thing. You said its awd? Price out the front end suspension and brake components and compare to the RWD variant.

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CENSORED due to not family friendly words