I am having the same mildew odor in my 2015 Lexus NX200. My husband recently took it in for service and had them to look at the fix the smell and the leaking in the sunroof. The sunroof issue seems to be resolved but not the odor, a matter of fact, the smell is getting worse every day! I am done with the Lexus vehicles. I was so impressed with the Lexus line of cars, but no more Lexus cars for me. I'm done!