$$GAS$$

I did a cost analysis based on 12,000 miles of annual driving and an average of 19 miles per gallon (mpg) fuel economy. I came out with a total of 631 gallons of gasoline needed for 1 year of driving at that fuel economy (19 mpg).
I calculated that I would be paying a total of $1,893 per year for gasoline if gasoline went up at $3.00 per gallon.
If gasoline was at $4.00 per gallon my cost would be $2,524 for the year.
So, basically, I would be paying $473 MORE per year if gas went up to $3 per gallon from the $2.25 where it was a few months ago.
Also, in another calculation which I made, I would be paying $1,104 MORE per year if gas goes up to $4 per gallon from the $2.25 per gallon low where it was a few months ago.
So, everyone's annual gasoline expense will increase somewhere between $473 to $1,104 more for the year if gasoline goes up to $3 and to $4 per gallon if you base the cost increase on the $2.25 per gallon low that we were all paying back a few months ago.

If you drive more than 12,000 miles per year in your Mustang, you gasoline costs would be more. So, anyone in here who drives a total of 24,000 miles per year in their Mustang would pay $946 MORE if gasoline went up to $3 per gallon and $2,208 MORE if gasoline went up to $4 per gallon if you base the increase difference in cost using the $2.25 per gallon low that we had a few months ago. The more mileage that you put on your Mustang, the more that you are going to pay for gasoline.
Do the math and you will see that I am right about what I am saying.

On another note, it's NOT worth it to go forward and sell or trade in your Mustang to get a more economical car if you already have a car payment or even if you don't have a car payment on the Mustang. The logic behind this statement is that you will still owe "MORE" money on a brand new car if you purchased another car brand new than if you were to keep your Mustang. If you opted to do things differently and purchase another brand new car with cash, you would still have to come up with at least $4,000 to $5,000 or more to make up the difference in the total price of the brand new car from the trade-in or sale value of your Mustang. Either way, it would take you anywhere from 5 to 8+ years just to recoup that $4,000 to $5,000 if you sell or trade-in your Mustang and purchase another brand new more economical car.

What I am trying to say here is that it's worth it to suck up the increase in the gasoline prices and to keep your Mustang because it will be a LOT CHEAPER to hold on to your Mustang than it would be to have to come up with another extra $4,000 to $5,000 for another car or to have a new car payment. It would take you a lot longer to pay off the car payment on another brand new car than it would to pay off the current car payment on your existing Mustang.
Considering all of these things, it's NOT worth it to sell or to trade-in your Mustang to get another more economical car. It may look like you are saving money on gasoline because the other car is more economical, but you are really not saving any money. You will be paying more money out in the different areas which I just described above if you buy a brand new economical car. The ONLY way that it would be worth it to purchase a brand new or even a used economical car is if your Mustang got totalled or if it was a huge money pit and needed thousands of dollars of repairs. Then it would be worth buying another vehicle.
You are much better off in keeping your Mustang.