Ever since BMW acquired the iconic Mini brand back in 1994, the two manufacturers have shared engineering platforms and heavy-duty chassis components. One major consequence of this shared German engineering is that modern Mini Cooper, Clubman, and Countryman models use the exact same high-security locking wheel bolts found on premium BMWs. Because they share these identical BMW security systems, Mini locking wheel nuts are highly susceptible to the exact same failure patterns. The most common culprit is the specialized "flower" or star-shaped internal pattern on the key header. 

There are several ways a Mini locking wheel nut key can fail, but this is one of the most common and frustrating scenarios. As shown in the image, the unique pattern that engages with the locking wheel bolt has completely snapped off the key. Once the key's internal teeth or "flower" pattern shears off, any remaining locking bolts on the car—typically one per wheel—are now effectively "stuck".

This is a less-than-ideal situation! Where a broken piece of the key remains wedged inside the bolt head itself. Different methods for removal are required for this but a good locking wheel nut removal specialist will make short work of it. You might get lucky and get this snapped part out but it’s not critical.