That's ok. It was just a theory. Unless you have records of mpg, acceleration etc under controlled conditions you'll nevrr really know. The best most of us can do is keep a record of fuel filled. Most of the variation in my mpg is down to length of journey/road type and of course enthusiasm. Even a long journey on a motorway will get low mpg with a heavy right foot!

I'll put it down to my improved driving skills!!  2013 Dynamic Santorini black
2011 XS Lago grey
2007 HLS Stornoway grey
sometimes towing an Elldis AVANTE 574.

Is it possible that disconnecting the battery has caused the various systems to forget thier learned parameters, and that the default parameters are actually better.

or your driving could have improved Tangiers Orange - gone, missing her
Replaced by Ewok what a mistake - now a happy Disco Sport owner

Further to this, after I had struggled to remove the battery I cleaned it, and found out it had got
a bloody handle!!  2013 Dynamic Santorini black
2011 XS Lago grey
2007 HLS Stornoway grey
sometimes towing an Elldis AVANTE 574.