Which BMW engine is the benchmark for reliability on the used market?
The B58 3.0L turbocharged inline-six fitted to 340i, 440i, 540i, X3 M40i, X4 M40i, X5 xDrive40i, Z4 M40i and Toyota Supra is currently the most reliable high-performance BMW engine available. Single turbo, closed-deck block, port-and-direct injection — the B58 has shown exceptional durability well past 200,000 km when maintained with proper oil service. Avoid the earlier N54 twin-turbo (2007-2010) unless fuel pumps, injectors and charge pipes have been addressed. The N20 four-cylinder timing chain issues (2012-2015) are another red flag.
























