JD Power's Initial Quality Study measures the number of problems customers experience with new cars in the first 90 days of ownership. MINI doesn't do so hot in the study this, finding its spot near the bottom of the ranking.
There are criticisms of the methodology though.
http://www.autoguide.com/auto-news/2014/06/fiat-flayed-2014-jd-power-initial-quality-study.html

There are criticisms of the methodology though.
A lot of the reported problems also have to do with Bluetooth and audio systems, which are still problems, but aren't as serious as other mechanical problems that could possibly happen.But the survey only measures consumers' impressions of new vehicles in the first 90 days of ownership. It doesn't reflect longer-term quality and reliability — J.D. Power conducts separate studies that analyze those. It was based on responses from 86,000 new car buyers who responded to an online survey in May.
http://www.autoguide.com/auto-news/2014/06/fiat-flayed-2014-jd-power-initial-quality-study.html