Is there anything I can do to enhance my car to gain more mpg or make the engine run better 

There is no magic solution to this unless you are prepared to spend hundreds or even thousands of pounds on engine modifications.

For the average motorist who does not want to modify his car the recommendations are same as they have been since the dawn of motor cars a century ago:

1/ Service it regularly.

2/ Maintain the correct tyre pressures.

3/ Be as gentle on the accelerator and brake pedals as possible.

Welcome Steven,

In addition to Cliff’s comments, I would like to pick up on ‘…..make it run better’. 
Do you have concerns regarding how your particular engine is currently performing - any changes it’s performance over the time you have owned it?

Kind regards,

Gareth. 

No everything great just wanted to get the best for my car as it’s my pride & joy. 

Thanks Steven,

I now understand.

Sounds like you need to take advice from a recognised and respected mapping specialist.

If you do decide to investigate that route, it would be well worth having a word with your insurers before committing. 

OK, probably just me, but convertibles aren’t usually bought for performance - more for relaxing and smelling the flowers with the hood down!