14-18 with a tiny engine in a mustang....
My friend claims low 20s with his 94 camaro with a V8...
Anyway, according to
Fuel Economy of the 1993 Ford Mustang you should get 20+ mpg easy. I'm going to take a stab that your tires are low and your engine needs a tune up (plugs, wires, cap, rotor).
Personally, I would look for another car with a better mpg base line. Since the car has been in a couple wrecks, I assume your not after the looks of a sports car. A non-mustang 2.3L performs just as well, I'm sure there is something out there to meet your tastes. Besides that, it looks like it is ending up being a money sink if you have in fact changed a lot of parts under the hood in only 7 years of driving it. My Toyota Camry with 303k miles I have drove for 2 years and only thing I did to that was timing belt (from oil leak), oil seals in front of engine, and is currently down due to the rear brake line rusting out.
Another thing to point out, do you have any idea how much money you would save if you got 30mpg vs say 15mpg per year? Going off your numbers 62 miles a day, 5 days a week, it would be just over 16k miles per year and $4300 at 15mpg or $2150 at 30mpg. In just one year you could pay off a cheap 30mpg car in fuel savings alone before any mods! Keep the mustang and fix it up while your daily driver saves you money
.