I contacted Reese and they said just because the hitch is rated at 4000# has nothing to do with the car manufacturers limits. The hitch is capable of the weight, but not the car.
Ford's Taurus, incl SHO, tow limit is 1000#. I'm going back to new Subaru Legacy with 2700# towing weight. I had a '92 Taurus I towed a 21 foot 3700# center console for 4 years on short trips and had no real problems, but it's a risk.
U-Haul said no consideration is given to the cars structure strength when they say 3500#, I thought they worked with Ford engineers, but they don't.
Having brakes on a trailer will help a lot. The greatest load on the hitch/car is when you brake hard. Hard stopping can increase G-forces by 15-25% over the trailer weight. Acceleration will never go over maybe .25% G. If your car bends the subframe or burns out a tranny, and has a trailer hitch, betch'a Ford would refuse repair under warranty. :angelnot: