Today on Miramar Road while waiting to turn left on Camino Ruiz I saw a tow truck coming down doing about 50mph towing a Silver Pine Mica Prius with dealer advertising plates. No flat bed, the rear wheels were on the ground and from the quick look I got as it passed was that the rear bumper looked awfully close to the ground and at that speed, I would think the smallest pothole or dip would destroy that bumper cover.:mod:
The recommendation is to tow with at least the front wheels off the ground, because the transaxle doesn't really like moving fast even in Neutral. (The wheels are permanently coupled to the motors and engine, you can do some serious damage if the computer's not controlling the flow of power.) If you can't get it into Neutral you definitely shouldn't have the front wheels on the ground. The grey plastic part of the rear bumper/fender - referred to as 'rear lower-side spoilers' - is not attached when the car is delivered to the dealer. One of the pre-delivery checks is to ensure that this has been fitted. This may not have been done yet when you saw it. Still, the body-coloured part could be quite close to the ground when towing with the rear wheels on the ground. (See ET - Exterior for information on the 'rear lower-side spoilers'.)
I remember reading somewhere, and cannot remember where, that if the engine is not running, the transaxle will not get any lubrication. So, when you tow it with the front wheels on the ground, the HSD will not get any lubrication and could burn up.