Flat or Dead-Flat Oil - Provides a completely flat, oil-based finish. Generally used on walls but not suitable for areas of high wear.
Like this, it will actually take quite a while to reach a number that is close enough to the yellow color you've chosen that you can't tell any difference (and mathematically, you will never actually reach an average of 4!)
What colors are prevailing - tonal or local, warm or cold?
Take off the chrome molding around both the windshield and rear window. You can pick up a special tool at your local Mustang shop or by mail order that removes these quickly without scratching paint. Of course your paint is probably not in great shape at the moment, so a large flat screw driver will also do the trick. For some classic cars it makes sense to even remove the windshield, but classic Mustangs have chrome molding that will help cover any slight overspray.
What emotions does it produce?
The area covered by a gallon of whitewash depends upon the nature of the surface, but ordinarily a gallon will cover about 225 sq. ft. on wood, about 180 sq. ft. on brick, and about 270 sq. ft. on plaster. The formulas mentioned will make from 10 to 14 gallons of whitewash. If a smaller quantity is desired, the amount of each ingredient should be reduced proportionately.
Analyze your existing paint. The first step before determining if a budget paint job will work on your Mustang is to assess the current condition of the paint. In many cases you can prep and paint directly over an existing paint job, but only if it's in solid shape.