Just look up cars in your area on ev-cpo or tesla-info. Both sites can help you screen for HW4 so you don't make a mistake. Or you can go to the dealler you're looking at and just look at the car itself, the HW4 models have no ultrasonic sensors on the bumpers and the cameras look a bit different as well (plenty of pictures online to look at them). They tend to have a red lens on them which makes it more obvious. The best is to just screen inventory on those two sites for your area.