MPG uk 14mpg normal

I read on forums people are getter like 18th in the city and stuff. I don’t daily this car as much but I reset my trip and I always do V-Power fuel and I’m getting around 14.3MPG in the city such as sometime to gym,work and shopping. I don’t drive that heavy. A few pulls from 1st or mainly second once she’s warm. She’s stage 1 atm not sure how much BHP as I got the car like that. But is this MPG bad or good. It’s worse than a MAZDA RX8. On the motorway I think mine was in mid 20s.

Is there ways to increase mpg and still Be able to drive good and have some nice pulls. Possibly is there any parts that’s causing this MPG too be low?