The BMW 525i refers to specific models of the BMW 5 Series sedan from different years, with details varying significantly by generation, but generally featuring a powerful straight-six petrol engine, rear-wheel drive, automatic transmission, and a focus on luxury and performance. For instance, a 2011 model offers a 2979cc engine producing 306 bhp, while a 2007-2010 model has a 2497cc engine with 215 bhp.