Naphthaleme (mothballs) does not work on rats, I put them all round my car and in firewood stack rats nest built next to mothballs, as I said in my post above clear all possible nesting sites I kill them any way I can with the exception of commercial rat poison all the homemade ones work it may be abhorrent to some people but I found it abhorrent to have 2 rat attacks on the wireing of a 6 month old car and a rat infestation with them getting onto my balcony sh--ing and pi--ing there diseases all over my BBQ now that is abhorrent (love this new word now I know what it means?.)
And now the weather has turned they will make a b line for anywhere cosy and dark place like your car -wood stack -shed -house ,killed 6 this week by wood stack I put my loaded traps and other potions in lidl plastic tupperware boxes with rat size holes cut in one side so dogs and cat can not get in the traps i use are American plastic and metal can give details if you want.
I have made water traps that also work large bucket or barrel a few inches of water in and a roller or see saw set up on top with peanut butter on rat falls in water glug glug or pop it with the air rifle,google getting ride or rats,the last 18 months I have devoted months of time and money to the sweet little fluffy things.
I also now have set up very bright lights under my car in the car port as they only like cosy dark places to nest seems to have worked for me, good luck but you will never get ride of them just control them.