Most modern cars do not demonstrate any additional mpg from break in. Mine hasn't in 24,000 miles now. Strictly climate and driving style differences for me. My lifetime mpg is 52 mpg. It would be closer to 54 mpg had I driven it all summer in the most efficient temperatures (where it is typically getting 57 mpg). Instead, I prioritized riding my motorcycle which gets 78 mpg in the same conditions. Mind you, I have a much more efficient model than you and limit my speed to 65 mph. But of course, you will be doing far better than your prior car.
I used to live in Baltimore and drive to Glen Echo once or twice a week in a front wheel drive only 1979 Subaru as about the only times I drove the car. I drove briskly, ahem, (bat out of ****) down the parkway or 95 and the beltway, and got a wonderful 29 mpg out of the Subaru. Finally ended up selling it in DC for $1,000 with 180,000 miles on it because I just couldn't get the sucker to wear out. Still miss it 20 years later.
2018 Kia LX HEV Metal Stream with Advanced Tech