Comment by allengeorge

My understanding is that the initial Mini models were made with Peugeot engines, which were underpowered and pretty unreliable. At some point BMW switched Minis over to use a Beemer engine, at which point quality improved dramatically. Mini has been on an upward trend since (as has BMW).

Anecdotally, someone in my family has a Mini with the BMW engine, and it’s been ticking along just fine. Maintenance is expensive though.