It's just a wiffleball. Probably a soccer mom thing but for young children's T-ball.
My guess is that they glued it to a magnet ( the disc ), and stuck it on their car for a sense of identity but without causing any irreparable damage to the car. These little things that give identity also have a side-convenience of making their car easier to spot in a parking lot full of cars that all look the same.
Here's a similar one (description says 12", but the pictures make it look closer to the car picture) https://www.amazon.com/Crown-Sporting-Goods-12-inch-Softballs/dp/B07CG8RT1J
Edit: Or a pickleball seems to have holes that are closer to the same diameter as in the one in the car picture, but that seems less likely to me just because pickleball is less common in my area. https://www.amazon.com/gp/aw/d/B01MDTU83P
I just picked up the 25oz of this one. Good pop out of the wrapper.
I’m more of a slap hitter but I was getting it well into the outfield on the fly the first week.
You might get more mileage from a Miken Freak model but it’s hard to beat that price.
Also try this link. Amazon and Just Bats have it at $140
there is also a black one which is what I have but it didn't show up.
I totally get that. Best thing you can do is invest in a tee and a bucket of BP balls. Regular tee work can do wonders for your offensive game. Defense is a little tougher solo. A somewhat bouncy ball and a flat wall is great for working on grounders plus a little bonus throwing work. I personally like this ball I got from Amazon Voit Sponge Center Softball, 12-inch https://www.amazon.com/dp/B0000CD9UQ/ref=cm_sw_r_apan_i_6P2M32BS8Q2Q83T54FBV Size and weight are pretty true to a game ball plus its super soft so there is no fear of damaging anything you throw it against. Also, inexpensive.
Sorry if I wasn't clear. This is the ball we are using:
Rawlings Official ASA NFHS Red Dot Fastpitch Softballs, 12 Count, PX11RYLA https://www.amazon.com/dp/B01JPFBKJ0/ref=cm_sw_r_apan_glt_fabc_6SMKJNNF9K6HEZZZDWF7