Yesterday going to work I got 45.4 mpg according to the cars trip computer. Had a slight tail wind, temp was 78 and very very humid. It includes stop and go in the city at 45 mph, 2/3's 70 mph interstate and some 55 mph highway. Seem to get the best when the temps are higher. This is at 4 to 4:35 am. Going home I got 34.5 mpg. A/C was on and working hard (95 degrees) and I drive a little faster going home for some reason! I do get around 40 going to work in the summer, winter is mid 30's.

I have a '14 6 speed manual, EPA says I should get 34 highway.

 

Well done! Warm-moist (i.e. light) summer air is nice when it is *just* cool enough to not require the A/C; that light air allows the intake system to lean out the amount of fuel being injected, but still allows for good atomization/mixture. Long story short, better fuel economy.