BMW’s iconic straight-six diesel, available in single and twin-turbo variants — the M57N2 TÜ2 being the most sought after. Renowned for its cast-iron block, mechanical robustness, and serious tuning potential. Produces 150–286hp in stock form but responds extremely well to remapping. For 4×4 conversions like the Nissan Patrol and Land Rover Defender it’s a near-perfect fit: massive low-RPM torque, fuel efficient on the open road, and far more refined than most factory diesel alternatives.

The modern successor to the M57 — everything great about the original, plus common-rail injection, sequential twin-turbocharging, and better emissions compliance, making it easier to certify in NZ. In its highest factory tune (N57S, as found in the M550d and X5 M50d) it produces over 380hp and 740Nm. For conversions where compliance and daily driveability matter alongside performance, the N57 is hard to beat.