If you do like I did when I first got my mav and watch the MPGs closely, you'll be tempted to keep RPMs low as possible as often as possible. That's what they call lugging- cruising around at lowest RPMs you can.
I see this assumption quite often, Ford pays our shop $165.25/hr for warranty work and we charge walk in customers $170/hr. Shops don't hate warranty work, it pays pretty well.
Imagine being a tech and having to roll up in some ghetto with thousands of dollars in tools and not allowed to carry to protect yourself. Or just trying to work in someone's steep driveway, dealing with a customer's dog in the rain and do your job 100%. All for no extra pay.
Ford advertises...
I think most people would find it useful if it were adjustable. I almost always turn mine off because my commute has a few stop signs and shutting the engine off immediately after I apply the brake only to start again immediately cannot be good. If I could set it to shut off 2-5 seconds after...