Call the police non emergency number 610-272-1111 to come by to check it out. If the cars leave when you do, they have a scanner, so mention that you don't want it to go out over the radio. Try to get the license plate number and the make of the vehicles for the police.

The police came and checked the ID of the driver of the burgundy SUV. It turns out she's a cousin of the woman who rents next door. The policeman told me that unless she was breaking the law, she can sit in the SUV as long as she wants(!) I think it's a nuisance and Lord knows what she's doing on her phone all that time every single day, multiple times a day.