[botsapper]

Lowest (FE & comfort) hanging fruit, especially here in the Southwest. Just make sure your shop knows your state's darkest allowable tint levels for the different window panels.
An additional efficiency mod list is paint color/reflectivity property. White/light silver metallic roofs (Minis, FJs, etc) or white/light silver met. vehicle body paint always helpful for cooler cabins. Also, higher night time visibilty = better safety.
Another trivia but black/dark cars need more car washes than white cars. Detailers report much higher frequency of appearance maintenance of darker vehicles. White paint, less water use. Better resource efficiency.