BMW S85 M5, M6 Reliability & Common Problems The BMW S85 is an absolutely gorgeous 5.0L V10 engine. With 500hp and an 8,250 redline the S85 engine sounds insane. Even as an older engine, its 100hp per liter is among the best for NA engines. It's hard to hate a naturally aspired engine making 500hp and revving to 8,250. However, the S85 suffers a few common problems that … [Read more...] about The 4 Most Common BMW S85 M5/M6 Engine Problems