I have always owned Crown Vics, and that will never change. This Crown has 292000 miles on it, and still runs like it's brand new. Never had to anything to it, and still doesn't need anything. I wouldn't have an LX, but the Interceptors have it all.
General design and the power of the Interceptor 4.6.
None, other than changing the plastic intake that a lot of people have had problems with.