The second-generation BMW 1 Series (F20 5-door, F21 3-door) holds a unique place in automotive history: it is the last compact car on the market to offer a rear-wheel drive architecture and inline 6-cylinder engines. Launched in 2011, it underwent a major facelift (LCI) in 2015 which not only corrected its controversial design but, more importantly, introduced the new modular engine family (B series), replacing the N series blocks which sometimes had questionable reliability. A second minor facelift (LCI 2) occurred in 2017, modernizing the interior and the iDrive system. It's a model with two faces: pre-2015 versions require extreme vigilance, while post-2015 versions are among the most reliable premium compacts on the market.
The BMW 1 Series F20/F21 is a car with a polarizing personality and reliability split into two eras. Before 2015 (Phase 1), it should be approached with extreme caution: the N13 (petrol) and N47 (diesel) engines are plagued by costly timing chain issues. Unless you have an impeccable service history with invoices for preventive replacement, it's best to avoid them. After 2015 (LCI), the situation changes radically. The introduction of modular engines (B38, B48, B47, B58) transforms the 1 Series into one of the most reliable compact cars in its segment. If you're looking for pure driving pleasure, a 120i/125i LCI or the superb M140i are future collectors. For high-mileage drivers, a 118d or 120d LCI (B47) coupled with the ZF8 gearbox is a formidable choice for efficiency.