I went to SmartFilm and got their top-of-the-line ceramic tint in 70% VLT, including the visor area of the windshield. I didn't want to go darker because I didn't want things to look dark inside the car.
4.1 is slightly better than I expected for this drive, based on my history. The elevation changes, the canyon carving, and some faster-than-my-norm highway driving led me to expect 3.9. I've averaged 4.4 mi/kWh over the 7600 miles I've driven my car; that's probably about 2/3 city and 1/3 highway driving. I usually crest 5 for my daily commute to work, but not only am I driving very smoothly, the drive is all suburban, I usually have a slight tailwind, I know the timing of the stoplights and can hit mostly greens, I'm not exceeding 50mph, I rarely need the climate control, and in the wintertime I'm doing my morning commute immediately after charging for 30-45mins so the battery is up to a good temperature for efficient driving. On a highway round trip to Tucson, I get 4.0 if I'm generally not exceeding 75mph, not needing climate control, and not using highway assist. The A/C definitely makes a dent, and the heater even more. I'm almost always in Smooth mode, with high regen, and I'm "coasting" the car (letting up on the accelerator just enough that the power meter is indicating I'm slightly recharging the battery) way ahead of stoplights whenever that won't interfere with traffic. There are other threads on the forum about driving efficiency that may help.