I'm just setting this up for any additions to your car that help mileage. Speak from experience.
Myself... I finally got my anti sway bar for the rear of my 14 Corolla LE. I can admit. This car needed this. It helps a ton. Am confident I will get better mileage with it.
Cornering faster, but smoothly. Stability in a strong cross wind with gusts. That bar has made a big difference. Also the pleasure of driving. Along with the OEM specified high performance tires. It all works beautifully.
I can't believe I waited this long to get this.
I hope the high performance tyres don't spoil your mileage. High performance usually means grippier, and grippier means more fuel used to shift them. Let us know how you get on.
The tires. That is what the Toyota Engineers decided on. High Performance that have a max pressure of 45psi. They're deflated down to 32. It's their thinking. Works great. Car ain't heavy. Nice ride, handling, and all. Nicest driving car in it's class by a long shot...by Consumer Reports.
EDIT: Rather than reply to next post.... I have Pirelli P7's on my Corolla.
I am of a similar mind. The manufacturer's tyres at their recommended pressure are ideal for me. It is just that performance tyres are not always the best for fuel efficiency.
I know that for my car, Hankook RA18 Vantra LT are only E for efficiency, whereas Continental Eco Contact 5 are B.