Normally when you think about wildfires started by humans, you picture things like a careless smoker or an abandoned campfire as the causes. You’d be surprised to know that it’s actually cars that are a leading cause of that in the USA. Take it from the agencies themselves. The California Department of Forestry and Fire Protection says vehicles are the source for 10% of all wildland fires in the country. That’s concerning enough on its own, but the Oregon Department of Transportation goes even further, stating that cars are actually the top cause of summer wildfires in their state. Of course, things can vary greatly between states, but the important thing to note here is that wildfires are overwhelmingly started by humans – the Western Fire Chiefs Association puts that share at roughly 90%, and out of that, cars, trucks, and dirt bikes all play a big role.

For example, in April 2026, a Jeep Wrangler ended up getting stuck in an area with a lot of brush and dry grass. The exhaust ignited the grass burning the vehicle and torching 20 acres of Florida’s Ocala National Forest. That may not sound like a lot, especially considering the forest as a whole spans 387,000 acres. But with wildfires on the rise in the USA — nearly 30,000 have started in the country since the start of 2026 alone, which is the most in two decades — many “small” incidents like this add up to massive ecological damage.

In this case, the driver had wandered off a designated trail and gotten stuck in Grassy Pond, a marshy patch within the forest. Crews from the Forest Service and Lake County Fire Rescue spent the night fighting flames and even had to return the next day to mop up hot spots. As for the SUV, it was a total loss.

But the cause isn’t always this obvious, as the car itself doesn’t always catch fire. Most vehicle-caused wildfires actually happen during normal drives, with the driver leaving the scene without any idea of the chaos they left behind. Even something as small as a stray spark when stopping on the side of a highway can set a shoulder on fire if it’s dry and hot enough.

Perhaps the most common cause is the catalytic converter, which is required on every car, along with the exhaust system connected to it. These hang low underneath the chassis, which significantly increases the chances of contact with dry vegetation. These parts run extremely hot; on a 4×4 off-roading, they can climb past 1,500°F, which is roughly twice the temperature needed to ignite grass. Fire investigators have also flagged how catalytic converters tend to snag road debris on their heat shields, which then smolders and burns while you keep driving.

Beyond exhaust heat, there are a number of other vehicle components that can start fires. Brake pads that badly need replacing will throw sparks every time you slow down. Sparks are actually a huge concern, and they can come from multiple places. Under-inflated tires can compress and cause the wheel to scrape against the road, driving on an exposed wheel rim, trailer chains, can all cause fires.

Red-hot carbon embers flying out of the exhaust pipe are another major concern. Vehicles that often head off-road, like dirt bikes, are required to be fitted with spark arrestors – little mesh screens that sit inside the muffler and trap those particles before they exit the pipe. Finally, in case you do end up starting a fire, it’s good to keep a fire extinguisher in the car to prevent it from spreading.