We use our Garmins that are auto specific and have never had an issue. Only time I would think there would be one is if you were on secondary roads. I remember seeing some low tunnels/bridges for trains in the chicago area I think it was and maybe one or 2 low bridges but again these were all secondary roads. As the one poster above recommended/said, only plan daily drive and not whole trip with one of these things. Old military habits die hard. Route recon on map and then plug in the destination for the day. Never had problems with this method plus you are more able to make variations as wanted/needed.
On the garmons they show a car and a truck, we use the truck but not sure really what it is supposed to mean. Also found that fastest route is generally the best vs shorter as shorter may take you into areas you dont want to be, but then fastest can also take to some of them but in our experience hasn't really.