Is the BMW M3 a good investment?

The thesis

The E46 M3 is the last naturally aspirated inline-six M3 and widely regarded as the most balanced of the lineage. The S54 3.2L produces 338bhp and remains one of BMW M's finest engines. Values have climbed steadily, with manual coupes now £20k–£30k for sorted examples in the UK. The 'big three' jobs (subframe, rod bearings, VANOS) add cost but are well-documented. Recent forum data confirms £20k is the new floor for sub-100k-mile cars with maintenance history. The cycle is mid-stage—early adopters have bought, but the car hasn't yet reached the stratospheric pricing of E30 M3s.