The manual of the choice for the Z3 is the Bentley Publications manual from the USA. It is a huge 1,150 page manual with excellent quality photos and diagrams.
It covers the M44 4-cylinder engine, and M52, M52TU and M54 engines of the Z3 (1.9, 2.3i, 2.5i, 2.8i and 3.0i).It also covers the S52 (US only) and S54 engine in the M Roadster and Coupe.Haynes (USA) and Chiltons (USA) also produce manuals for the Z3, although they are part of their 3-Series manuals. They are limited to the 1.9 (M54), 2.3i and 2.8i models (M52).The Computer Outpost
PO Box 87
Hazelbrook NSW 2779, Australia