Hi, hope you guys are well.

I wanted to know if 38-40 mpg is ok for a ford fiesta 1l ecoboost 64 reg for normal city driving with a mix of stop start traffic. I usually do short journeys 10 to 15 mins. When it comes to acceleration, I usually let it go to 2000 to 2500 rpms before I change gears. I was expecting to get 45 mpg. Could the type of fuel I use make a difference for example using a local supermarket e10 fuel vs shell e5? 

Any thoughts would be appreciated 

Thanks

Hard to answer mpg questions as circumstances and driving techniques differ widely.

From my experience with a 1.0, I'd say 38-40 is doing ok for the conditions described. 10-15 minute journeys are not great for mpg as the engine never warms properly, and are particularly bad for an ecoboost with the wet belt issues.* 

(* Your car is due for a belt change at 10 years maximum, I don't think you mentioned having it done in any of your other posts?)