The BMW 5 Series E60 (sedan) and E61 (Touring/wagon) marked a major stylistic break under the Chris Bangle era. Highly controversial upon its release, its lines have ultimately aged remarkably well. It introduced cutting-edge technologies for its time: iDrive multimedia system, active steering, head-up display, and an aluminum front section for ideal weight distribution (50/50). The March 2007 facelift (LCI) brought improved interior finish, a more reliable iDrive, LED lights, and a complete overhaul of the engine range (transition to direct injection gasoline and new diesel blocks). Although its road qualities are exceptional, it is a complex vehicle whose electronic and mechanical reliability (depending on the engines) requires rigorous monitoring.
The BMW 5 Series E60/E61 is a formidable road car that offers a rare driving pleasure for its size. However, it is a complex car that does not tolerate approximate maintenance. For a diesel purchase, the top choice is the M57 6-cylinder (525d or 530d), preferably in the facelifted (LCI) version to benefit from the more reliable iDrive and better finish, provided the swirl flaps are removed and the manifold is checked. Absolutely avoid the 177hp 520d (N47 engine) due to its timing chain, unless the repair has been recently done at BMW. Plan for a reserve budget for electronics and running gear.