According to a paper published on May 12, 2016 in the Journal of the American Medical Association Ophthalmology, Americans have more cataract on the left eye and skin cancer on the left face than the right eye and right face, respectively, because drivers sit on the left side, and because UV-A, the major UV component responsible for skin wrinkles among other effects, is not blocked efficiently on the side window. (The windshield blocks UV-A almost completely.)
The paper also tabulates the efficiency in UV blocking by the side windows of various automobile models. 2013 BMW is the worst, blocking only 55%, while 2011 Lexus blocks 96%, which is the best. If you drive a car with poor UV blocking efficiency on the side, drive less, use sunscreen, or install a UV blocking film on the left window.
