I didn't say that the 4.0L was perfect, or superior to the 3.7L. I'm simply saying that it isn't rough enough to be an annoyance to me (or either of my parents) and that it isn't a horrible engine. Heck the most annoying thing about the mustang is the durn transmission. It shifts with a very noticable, I don't want to say jerk, but I don't know what word to use. It isn't rough, but it is very noticeable. (This is the French-built 5 speed auto). But I am glad they decided to replace the 4.0L, but I don't expect my mom to replace the current mustang, as she is perfectly content, and pleased with the 210 ponies she has now.