In an age when most car companies have shifted toward building the more compact V6 or a turbocharged inline-4, BMW has kept a candle on for the venerable inline-6, the best six-cylinder engine. In constant production at the Bavarian manufacturer since the 1930s, the straight-6 allows for greater balance and fewer parts than a V-engine. It provides for smooth power delivery and can handle a range of uses, from off-roaders to performance hounds.
One of BMW’s more popular offerings in this layout was the M54 (in production from 2000 to 2006). While BMW engines are generally considered pretty solid, the M54 was stood out for its great balance of power and efficiency when stock, and it was extremely modder-friendly to boot. Even better for long-term owners, it has developed a fantastic reputation for reliability, too. So while it’s not as advanced or powerful as its modern offshoot, the B58, might it be a better choice?
Fortunately, the B58 has also proven to be a dependable piece of machinery over the long haul, and across its 10-year (and counting) lifespan, it does not appear to have developed any major problems. So in terms of reliability, which of these two engines you have matters less than making sure you bring it in for maintenance regularly.
What are some common issues?
While both engines have great longevity, they do have a few things to watch out for. The B58 occasionally sees coolant levels drop suddenly in the primary reservoir, which in turn leads to overheating. Perhaps not as a coincidence, other somewhat common issues involve the valve cover gaskets failing due to overheating. Even here, however, the B58 isn’t all that different from the M54, which saw similar issues throughout its life cycle. In neither case were these problems all that frequent, however.
Both engines also use BMW’s VANOS, a variable valve timing system. Given its complexity, it’s not a surprise that it can be a relatively common point of failure, particularly around its solenoids, which apply oil pressure to the system. The modern B58 version of this system is more advanced and slightly harder to repair than the older M54, but this really shouldn’t be a dealbreaker if you’re thinking about the earlier engine.
