1-Series vs A-Class. Reliability Index:. 1-Series: 136 A-Class: 132. The 1-Series is BMW’s smallest model and is also one of their most popular in recent years. First and second-gen cars were rear-wheel-drive ordeals, with BMW deciding to make the switch to a new FWD platform for its 1-Series just a year ago. 2023 BMW 5-Series Quality and Reliability Ratings J.D. Power Quality and Reliability ratings are a combination of quality and dependability scores. Quality scores are based on initial We expect the 2024 5 Series will be more reliable than the average new car. This prediction is based on the previous generation 5 Series, plus the BMW brand scores. The 2020 BMW 5 0zvVIR.