I wouldn't know at this moment in time about the improved efficiency of the bulbs I purchased, but they worked when i put them in during the daylight hours (i rarely go out at night but on the odd occasions I do I have found the Mercedes CLK lights not that special although I imagine they have improved over the years (mine is a 2000 model) Your service was good and cheaper that Euro parts but after postage no difference in the final cost and I had to wait in. In future unless there is a considerable price reduction I will stick with euro parts because of excessive postal charge. Trevor Richardson