Road tripping this week in my wife's 2015 Miata with 6 speed auto. Couldn't resist a little mild mpg play along the way! I set tires to 35 before we left.
I think the most she's seen in this car is low 30's on short trips across FL. Her typical DD mpg is 21-24. Daily drive is a 3-mile trip. The car never even gets warmed up, and spends much of the time waiting at traffic lights.
Her previous 2007 Miata, I maxed out at 34 mpg once, but never really tried that hard.
Clearwater, FL to Jekyll Island, GA. About 6 hours. Mostly 55-60 mph, mostly back roads, not a lot of traffic. No real Hypermiling, just driving with a light foot, extending coasts, and keeping speed below 55 as much as possible.
Dash display got as far as 35.6, and the day ended at 34.9 or so. Fill up was inaccurate because the was about 1/8 tank of City driving before I started. I reset the mpg meter when we left for this trip.
Inspired by day 1... I really wanted to see 38 mpg. Want optimistic after the first half of the day barely got me to 36. But, it was windy. (Every which way... But definitely some cross winds and head winds) And coming inland from the coast, it was predominantly uphill.
As things got a little hilly, and the wind settled down, the mpg started slowly climbing. Just a tenth every 10 minutes or so... But it was there. Peaked at 37.6.
Then we started getting into some small towns and traffic that messed it all up. Ended the day with the display reading 36.6. 345.9 miles and 9.586 gallons. Actual 36.08 mpg.
Now we're in the mountains, and I'm having fun! Averaging closer to 27 mpg.
May try for 38 again on my way home. I know I could easily do it with some neutral coasting. Not sure if my wife would like it. She doesn't complain about me manual shifting it...