2007 Ford Focus electrical issues(?) and declining mpg

I’ve had my 2007 Ford Focus for 5 years, having bought it used when it had about 20,000 miles on it. Now I have about 59,000 miles on the car. I have 3 concerns: 1) The Focus is an SES and has a multi-CD player. About a year ago, I noticed some of CDs were sounding off-key or slow and they were very hot when I took them out of the player. Eventually the player stopped working and now just says “bad disc” when I put a disc in.
2) Coincidentally (or not), the driver’s side airbag warning light kept going on and off for months last summer and fall, usually after very humid or rainy weather. Oddly, it has not happened this spring or summer in spite of lots of rain and humidity. I don’t know if these 2 problems (the CD player and the airbag warning light) are related. Could they be due to an electrical problem in the dashboard or something else? Also should I take it to the dealership where I bought it to get it fixed? I have some miles left on a warranty, but am not sure the CD player or warning lights are covered.
3) I used to get 23 mpg in the city and now it has dropped to between 18-20. On the highway, it’s better, about 25-27 mpg, but used to be about 30 mpg. I do the oil changes, check the tire pressures, replaced 2 tires last year, etc. My mechanic said the car is just aging and will lose its mpg rate as it gets older. Is this true? He also says it needs a transmission flush (for about $200!) and new brake pads. Could these have anything to do with why the mpg rate has decreased?.

The trouble with the CD unit and the airbag warning light are most likely due to separate issues I would have to say. One or both of the problems could be covered under your warranty but you would have to read the fine print of the contact to find out or call the company that is carrying the warranty contract and see what they say about those things. Even the best contracts can be limiting with their coverage of things.

I think replacing the CD unit will fix that issue and the airbag problem would seem to be due to a wire connection problem possibly in the power to that circuit or with the connection to the airbags. Replacing sparkplugs, cleaning the EGR valve, replacing the air filter if it is dirty, are all things that could cause the gas mileage issue. Even though the car is aging I don’t think the mileage should change as much as you say it did. Something is wrong and needs to be fixed. It sounds like your mechanic has given up the fight on it.

If the brakes have never been worked on then you have done well with that set and they most likely have little life left on them. So replacing the pads should be done before also damaging the rotors or drums. I wouldn’t be surprised if the scheduled maintenance calls for a transmission fluid change at this point and may be over due. Follow the Owner’s Manual scheduled maintenance intervals to help keep the vehicle in top shape.

Could be a bad connection in the wheel to the bag or maybe the seat belt switch. They can read the fault and tell what component the computer thinks has a problem. Was this car ever in a wreck? If so, someone may have replaced the bag. CarFax does not always report but maybe it will show up. CD unit probably is toast. Cougar is correct on all the normal mtc that needs to be done that would affect mileage.

@MomTaxi

Here is your maintenance schedule, in case you don’t have yours handy

http://www.fleet.ford.com/maintenance/maintenance-schedules/

I am against the flush. Drop the pan, replace the fluid and filter. Your pan does not have a drain plug, so it must be removed to drain the fluid. Make sure to use the correct Mercon transmission fluid.

It is possible that your mechanic wants to do the flush, because it’s less messy for him.

It looks like you’re also due for that second set of plugs and the second fuel filter by now.

I highly recommend replacing the coolant, if you haven’t done so yet.

About the Focus 2007:

I replaced the coolant at 70,000 miles; it is a very cheap procedure and seemed due six year.
Second set of plugs?? Will check but I think they were supposed to last to 90 K to 100 K ???

I checked the transmission fluid at every oil change. Should have replaced it but I would only go to a dealer for that. Who wants the local guy near the transmission. ???

All in all the 2007 was a great model year and I had very good luck with it !