You're probably way overdue on the filter change but what "they say" is a
lie.  It DID make a big difference in carbureted cars

The average driver ( who rarely puts the pedal to the floor) wont notice
a dam bit of difference... BUT dirty air filters lead to dirty MAF
sensors and THEY will cause performance problems.

And gonzo plugs wont give you 10% better mileage, either. If they did,
wouldnt the Mfrs use them in the first place?

Neither will the "Air Spinners" you see on late night commercials..If
they did, wouldnt the Mfrs use them in the first place?

And when they talk about tire inflation and mileage, they're talking
about BIAS ply tires which no one in their right mind buys anyway... even
if they can find them.  Of course with an explorer, you keep s your
inflted properly anyway, unless you have a death wish.

Sidenote:  Once saw a "professional" demonstrate how driving 55 saved 15%
on gas compared to driving 65.

He did it on a small road course track with a corner coming up every few
hundred feet.  IOW, he was a liar.

If it's "Conventional Wisdom" and you hear it on the news or a
commercial, it's probably an exaggeration at the least.

But the topper was a cop on local news discussing a congested area of
freeway who advised everyone using that stretch to slow down and leave
more distance between cars... what a freakin' idiot!