The drain line is 3 or 4 inches inside diameter, so unless there is a partial clog downstream for it to get caught in you are probably safe as long as it got through that toilet. I'd be extra alert for back-ups in the next couple of days, though, just in case; that toilet in particular.

I worked building maintanace for 25 day cares and toy in a toilet happened at least 3 times per week so I have some experience.
Let's test to see if the car is in the toilet. Flush the largest wad of toilet paper you dare and if it goes down without hesitation,wait until tank fills and turns off then flush another huge wad. If the secound wad fails to back the toilet up,shout yippee and consider the car a non-issue.
But,,,,,,as Randy Travis sang,,,,,on the other hand,,,,,,if it backs up.
3 out of 4 times the object will lodge in the toilet between highest point of loop in toilet and the floor flange. If an object clears the floor flange,it rarly causes any trouble.
1st order of business is,does the car float (have mom try another car from the set in a sink full of water. A sinker is difficult but a floater is near impossible to retreive with a closet auger unless you dip all water out of bowl.
If the toilet backs up,I dip and sop the bowl dry then use a mirror to look in the toilet similar to how a dentist does. If I see the object,I use a bent coat hanger while looking in the mirror to pull the object out. If it backs up but I can't see the object,I use a closet auger on the outside chance it will hook it. From there it's pull the toilet and go at it from the bottom.