I was never sold on the transmission Ford uses in the Focus and Fiesta, for flat towing. Nor was I keen on the idea of having to disconnect the battery every time you flat tow. That pretty much took the Focus and Fiesta off of our list (even before I read of several stories like this that just confirmed it even more).
We ended up going with the Ford Fusion hybrid, and have been very happy with it. Just seemed like a much better choice. No need to disconnect battery or anything, no crazy procedures to go through when hooking up. Just throw it in neutral, hook up and go. Not sure all the details of why, but Ford's hybrid drivetrain they use in the Fusion and CMax hybrids lends itself really, really well to flat towing.
After over 4 years of use as my daily driver and flat towing (its a 2013 model), nearly 80,000 miles on the Fusion (and probably another 20k worth of flat towing miles)....Car still runs, drives as good as the day I bought it. Only thing its ever needed is routine maintenance (oil changes, etc), a set of tires after like 60k miles, and a (12 volt) battery.
Will and Cheryl
2021 Newmar Baystar 3014 on F53 (7.3 V8) Chassis ("Brook")
2018 Jeep Wrangler JK ("Wilbur")