After 23,000 miles, not one problem. The build quality does not disappoint as in some previous Mercedes. The performance and economy of the diesel engine is unbelievable. My round-trip comute of 36 miles averaged 19 mpg in a 6 cyl. Grand Cherokee; the E320 averages 32. Best mileage was 41 for a long road trip and never lower than 26 in city driving. The diesel definitely prefers hot weather as highway milage drops about 4 mpg in the winter. The small items of bad news: the electric brakes have no reason to exist, there is no oil dipstick, the electronics are difficult to set, the stone colored carpet and mats are impossible to keep clean, and MB is not interested in owner feedback.
The combination of performance and great fuel mileage followed by excellent build quality.
1. Offer a tan/brown interior option and darker carpet on the stone color. 2. Needs to be more servicer-friendly for routine maintenance and fuel filter replacement. 3. Dump the electric brakes. 4. Simplify the control settings. 5. Adopt BMW's included service plan, not their ugly rear design.