BMW 5 Series EfficientDynamics.
What to Check Before Buying.

The BMW 5 Series EfficientDynamics is ideal for high-mileage drivers seeking executive comfort with lower running costs, particularly company car users benefiting from reduced benefit-in-kind tax rates. This diesel variant delivers impressive fuel economy, often exceeding 50mpg in real-world driving, while maintaining the refined driving experience expected from the 5 Series. However, the complex emissions reduction technology, including diesel particulate filters and EGR systems, can prove expensive to repair outside warranty. When inspecting a used example, check the service history meticulously for proof of regular oil changes using BMW Longlife-04 specification oil, as this is critical for DPF longevity. Test the stop-start system functions correctly and examine for excessive oil consumption, a known issue on some units. Request evidence of any software updates addressing EGR valve failures. The auto start-stop battery is costly to replace, so verify it holds charge properly. Given the higher complexity compared to non-EfficientDynamics models, a comprehensive pre-purchase inspection is worthwhile to avoid potentially significant repair bills on these otherwise capable and economical executive saloons.

The average used car has 3+ known model faults the seller won't mention.