E30 M3 common rust spots, check these before buying

The E30 M3 has several known rust traps that can turn a bargain into a money pit. Check the front inner wheel arches behind the headlights, the jacking points, the battery tray area, and crucially the rear quarter panels around the flared arches. The M3-specific wide arches trap moisture at the seam where they meet the standard bodywork. Also lift the rear seat and check the floor pan. A car with structural rust in the rear quarters will cost $10,000+ in panel work. Every dollar spent on a pre-purchase inspection is money well spent.