Not sure, the poor thing probably crawled up from the engine compartment through the floor boards. I would stop by your mechanic, have them put the car on a lift and investigate as to how it entered and see what you can do to close the hole up, if possible. Or use chemicals? Not fond of using chemicals unless absolutely necessary. See if these help?
Find out how they are getting in and fix it. 😍
How are they getting in? Are your windows open?
Park the car on those orange ramps that mechanics use.
Most frogs cannot jump that high to get into your car.
...also - park as far away from swampy land as your neighbors will allow.