Most motorists do not own a self-driving vehicle. Yet autonomous automobiles have become an increased presence on American roadways. Automakers like Tesla, Volvo and GM produce vehicles with advanced self-driving systems. And others will begin testing such vehicles soon.

Many people who own autonomous vehicles think they can take their hands off the wheel or their eyes off the road. But most of these automobiles still need a driver to perform overrides. And while some drivers may nap or watch movies in their self-driving car, that doesn’t mean you should.

If you own an autonomous vehicle or have thought about purchasing one, consider these facts before you put it on autopilot.

Most self-driving cars are not fully autonomous

Most autonomous vehicles do not have systems where the driver can relinquish all control. But some can safely enter autopilot mode on the highway. Autopilot, in this case, means that the car’s speed and steering are self-controlled under stable road conditions. And some vehicles, like Tesla models, can park without human help. Yet automakers have warned against using these systems by default. Doing so is a safety risk because they cannot yet substitute for human interference.

Human engagement makes autonomous vehicles safer

Self-driving vehicles could help reduce motor vehicle accidents and fatalities. Yet high-profile collisions have sparked concerns about the impact of these automobiles. Most of these accidents occurred because motorists abused the power of self-driving systems. Trusting your vehicle’s technology doesn’t permit you to engage in distracting activities while on the road. If you focus on your surroundings, you retain the ability to take quick, decisive action when necessary.

Autonomous vehicles could make roads safer. But improved safety can only happen if you pay attention while behind the wheel of your self-driving car. Knowing the limits of your vehicle’s systems can help you take a step in the right direction.