BMW has had some reliability misses in the past (especially with past V8 engines), though their current B48/B58 engines are very reliable. Porsche has a very extensive vehicle testing process before their models come to market, and they have always been known for good reliability (though they have had some misses in the past, like M96 engine IMS bearings and bore scoring from the early-mid 2000s, and 991.1 GT3 engine failures).