Replaced Brake Pedal Switch - Increased MPG?

I was getting the Exclamation/ABS/VSC warning light combo about 6 months ago and had my skid control unit replaced which fixed the issue. Strangely my MPG seemed to take a nosedive from 49/50 on my daily commute to <42.

Earlier this month the lights were back. Having had the skid control unit replaced I decided to try replacing the brake pedal switch myself. After dismantling the dash and getting to the switch it turned out the new switch I had only had 2 connections rather than 4. Regardless I gave it a go. A few days in and no errors later my MPG has jumped to 50+. Any ideas why this could be?

Cruise control doesn't work - I guess the missing connectors were maybe used by that?

Prior to replacing the switch, Techstream was reporting the same error across ABS/VSC and Cruise Control units

 

Before replacing the pedal switch I had:
P0571 and P0607 on the Hybrid and Cruise controls.
C1249 (open circuit in stop light switch circuit) on the ABS/VSC/TRC

Now I just have a P0571 (brake switch A circuit) on the Hybrid and Cruise Control.

If I try and turn cruise on, the word flashes a couple of times and disappears

Any thoughts?