I think you can reasonably expect a few percentage points of improvement as your car gets some more miles under its belt (like 4-5,000 miles). So maybe an extra 1-1.5 mpg.
You should see your car's mileage improve over the next 6 weeks, especially if you live in the northern part of the country. The 2 biggest factors that will help your mileage as we get deeper into Spring are...
1) warm outdoor temps
2) no more winter blended gasoline
Another factor is that as you drive the car and watch your Scangauge, you will learn what driving habits will allow you to extract the most mileage from the car. I'm not talking crazy hyper-miler stuff like engine-off coasting. I'm just talking about reasonable driving modifications.
I have seen an improvement in my mileage just from last week. It's mainly due to the increasing outdoor temperatures. I don't know where you live, but we had temps in the 20s last week and my car struggled to average 48mpg for the last 7 days. Today it's 70+ and the car is easily going to clear 50+ mpg this week with no other changes.
As soon as we have consistently warm temperatures and winter-blended fuel disappears, I expect my car to be back to the low 50's.
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View my fuel log 2015 Mirage ES 1.2 manual: 52.2 mpg (US) ... 22.2 km/L ... 4.5 L/100 km ... 62.6 mpg (Imp)