For me, I got the correct oil and oil filter put in.Did they use the correct oil? Wrong oil type can affect mpg. The 2.4 Renegades use 0W-20 low viscosty and the 1.4 uses 5W-40 synthetic. Check your invoices for oil type used.
I came back a week later because of the MPG issue and they said every vital is fine but they recalibrate the MPG calculator just in case. So far, nothings changed