I've used it (fuel fragrance with top lube) in my personal alcohol injected BBC years ago as well as in a blown alcohol car that I helped crew for. Most people use it for alcohol burning engines to make the exhaust LESS obnoxious. Very rarely have I ever seen it used in a car running gasoline or leaded race gas. If your Mustang stinks it probably needs attention elsewhere besides an additive, likely in the tune department. That being said this product does have a place and a legitimate use, without more information I'm inclined to say your Mustang isn't one of them.