DIAGNOSIS The default motion zones and sensitivity are too broad. The "People Only" mode uses the onboard AI chip, but it still scans the entire zone you've set. If your zone includes the street, it will detect the car first, then realize it's not a person, but you'll still get an alert.
FIX Open the Ring app, select your device, then go to Motion Settings. First, adjust your Motion Zones. Draw the zone to cover ONLY your walkway and porch, explicitly excluding the street, driveway, and swinging tree shadows. Then, slide the Motion Sensitivity down to about 60-70%. Finally, and most importantly, ensure "People Only Mode" is toggled ON.
IF THAT DIDN'T WORK If you're still getting car alerts with People Only on, the car's headlights at night might be triggering the infrared sensor before the AI can classify it. Go into Smart Alerts and try disabling "Motion Alerts" at night, leaving only "Ring Alerts" (when someone presses the button).
HEADS UP The Advanced Motion Detection (which includes People Only) is a Ring Protect subscription feature. If you don't have an active subscription, you won't have the option to turn it on, and you'll get all motion alerts.