Why miles to empty suddenly much lower?

So I have a 2016 Ford Focus that I have had for a few months now. When the gas tank is FULL it has always read over 430 miles to empty, until this week. Suddenly I filled it up today and it says I only have 186 miles to empty? Seriously wtf…

Yes I do park my car facing downhill but that hasn't changed since I bought the car.

The only other thing different than usual, is my having to run the car almost to empty this week, having to wait til payday. (Normally I fill it when it gets to 1/4 tank) But I don't understand how that happening would affect my tank so much?! Seriously it says less than half of what it normally does and yet the gas needle is up past full.

Can anyone tell me what is wrong?
Also is this a false reading and I will still get my regular amount of miles? Or am I really about to get significantly less miles on this tank? I'm really worried because I do drive my cat quite a bit and am worried now I will have to pay more than double for my gas.

Any info please and thanks!

Is this VW Jetta worth saving?

I have a 2006 VW Jetta. I had some issues with it and issues with a mechanic that worked on it. The car seemed to be fine and then the newly replaced oil filter had a cut in it and oil gushed out- mechanic said it happened in his garage "probably" and replaced the filter. Never going back. The car hasn't been right since. Now a big fan makes noise. Took it to two places (during a super hot day) because check engine light came on then disappeared. Each place ran a diagnosis that sad fan relay issues. Currently AC still works but big fan sounds like a jet landing. I'm unsure of cost. The problem is the car has a small rear main seal leak, and now this. Money is something I don't have flowing for repairs. If I managed to scrounge enough money to fix the fan, at least, is the car still worth the save.
I learned my (hearts desire) lesson on Euro cars. What would be a better car on cost, Ford Focus possibly?

Is it my alternator?

I have a 2004 ford focus zx3 PZEV and when I turn my headlights on they flicker a little. This also happens to the interior lights as well. At idle when the rad fan kicks on the lights dim significantly until I start to drive again. I used a multimeter and with the car off get a reading of 12.4 volts. With the car on and no lights, radio, AC, it bounces between up to 14.2v and 14.4, with all those things on after about 5 minutes it bounces between 13.6 and 14.2v. It eventually got as Low as 12.6 and stayed more constant.

Let the master cylinder run dry and now the brake pedal goes to the floor when I turn the car on. Is air still in the system?

I pulled the car out of storage and i noteced the left front caliper was leaking so I replaced the caliper. The only problem was the master cylinder ran dry. I bleed the brakes three times. I did not see any air in the lines after I bleed them a third time. When the car is off the brake pedal gets rock hard when the pedal ia depressed about half way. With the car on the brake pedal goes to the floor. Would this be cause by air in the system? The car is a 03 ford focus.

Ford focus 2000 AC not working?

So one day, I changed my AC speed from 4 to 2 and then the AC button light went away and my AC went out. I changed the blow motor because two people told me that was problem because there was electricity flowing through it. When I press the relay for the AC in the fuse box, some part of the AC under the hood makes a noise (the noice it makes when my AC is on) but the AC doesn't turn on nor will the light turn on. Also, if it's the fuse, which fuse would it be?