I have a 2008 and have tried to be very careful when pulling up to a parking curb because I have learned that the front end bumper/undercarriage of a Prius is very low. But either someone backed into me, or I hit something pretty hard, because now I have a fairly good-sized "ding" on the part right below the grill. Any ideas on how to smooth it out or how to avoid future dings by putting something over that part? I have a clear glued-on cover over the trunk "step-up/bumper" and it has worked really well. I might have the same thing put on the front end under the grill but would like to first try to repair the ding as much as possible. Thanks.
I doubt that a 'clear glued-on cover' would have helped much. You could try some touch-up paint to help mask the damage. I had numerous dings and chips in my 04 and just lived with them. With low ground clearance, it's had to keep road debris from impacting that area. The other option is to ask a body shop if they can inexpensively fix/hide the damage.
I put a bumper guard on the bottom center of my Prius. I also have stick-on clear protector(cheaply one) and it did protective my lower grill from scratches. It was unfortunate that a piece of plastic flew off the back of a pick-up on the freeway and dented/tore the left side lower grill. Too bad my bumper guard was only on the center or else it would have protect it.
It's plastic so very hard to repair. It's also very difficult to get in behind that part if you did want to try to push it out. Lots of fasteners to remove. I might try a heat gun to see what would happen but that's probably not a good idea. You may have to live with it until something worse happens.
If I were you, I would just take a buffer/polisher and polish it. The ding will still be there, but would not be as obvious.