Ever seen a car with bright green lights and wondered what it was about? At first glance, it might seem like a festive touch or an early celebration. But these lights aren’t just for show—they serve a real and important purpose. Green lights on vehicles are a sign that the car is part of an emergency medical service.

When you spot one, it’s a signal to yield the right of way—because someone inside could be heading to receive critical medical attention. You’ll typically see green lights on volunteer EMTs, private medical transport services, or non-emergency ambulances. While these vehicles aren’t rushing to life-threatening situations like traditional ambulances, they’re still on important missions, transporting patients to necessary treatments, dialysis, or healthcare appointments.