What Self-Driving Cars Are and How They Operate

A self-driving car (also called an autonomous vehicle) is a car that can navigate, steer, and brake itself without a human driver controlling it. Instead of a person at the wheel, the car uses cameras, radar, lidar sensors, and computer systems to detect the road, other vehicles, pedestrians, and traffic signals—then makes decisions about speed and direction based on that data.

Self-driving cars exist on a spectrum. Some cars on the road today have Level 2 automation, meaning they can handle steering or acceleration for stretches of highway, but a human driver must stay alert and take over when needed. Others are being tested at Level 4 automation, where the car can drive itself in specific conditions (like a defined city area) without a human driver present. A fully self-driving car with no steering wheel or pedals would be Level 5 automation—that does not yet exist in consumer vehicles.

The difference matters for you as a driver or passenger. If you own a car with Level 2 features (like Tesla Autopilot or Cadillac Super Cruise), you are still responsible for watching the road and taking control. If you ride in a Level 4 robotaxi in a city where they operate, the company running the service is responsible for the vehicle's actions.

Key Takeaways

  • Self-driving cars use cameras, radar, and lidar to sense their surroundings and make driving decisions without human input.
  • Most cars sold today have Level 2 features that information with steering or speed, but require a human driver to stay in control and watch the road.
  • Level 4 self-driving cars (robotaxis) are being tested in limited cities and can operate without a human driver in defined areas.
  • Insurance, liability, and safety standards for self-driving cars are still being written by states and federal agencies.

The Technology Inside a Self-Driving Car

Self-driving cars rely on multiple sensor types working together. Cameras capture what the car "sees"—lane markings, traffic lights, pedestrians, and road signs. Radar bounces radio waves off objects to detect distance and speed, especially useful in rain or fog. Lidar (light detection and ranging) fires laser pulses to build a detailed 3D map of everything around the car.

All this sensor data feeds into onboard computers running machine learning software. The software has been trained on millions of miles of driving data to recognize patterns: what a stop sign looks like, how a pedestrian typically moves, when a car ahead is about to brake. The computer processes sensor input dozens of times per second and decides whether to accelerate, maintain speed, or brake.

The system is not perfect. Self-driving cars can struggle in heavy snow (which obscures lane markings), with construction zones that change road layout, or with unusual situations the training data did not cover. They also cannot yet read a police officer's hand signals the way a human driver can.

Self-Driving Cars Available or Being Tested Now

Level 2 systems are in millions of cars on the road. Tesla's Autopilot, Cadillac's Super Cruise, and BMW's Driving Assistant Plus all let the car steer itself on highways for extended periods. Newer models from Mercedes, Audi, and others are adding similar features. You can buy these cars today, though the features cost extra and require a subscription in some cases.

Level 4 robotaxis are operating in limited areas. Waymo (owned by Google's parent company Alphabet) runs driverless taxi services in San Francisco, Phoenix, and Los Angeles, with plans to expand. Cruise (owned by General Motors) was testing robotaxis in San Francisco but paused operations in 2024 after a collision. Other companies like Zoox and Baidu are testing in China and other regions.

These robotaxis are not for sale to consumers. You request one through an app, the car arrives without a driver, and you pay per ride. They operate only in mapped areas with good weather and defined routes—not across the country or in heavy snow.

How Self-Driving Cars Affect Insurance and Liability

If you own a car with Level 2 features, you are still the driver. You hold the insurance, you are responsible for accidents, and you must stay alert. The car assists, but you control it. Your insurance company may offer discounts if your car has safety features like automatic emergency braking.

For Level 4 robotaxis, liability shifts. If a Waymo robotaxi hits another car, Waymo's insurance covers it, not the passenger. The company operating the service is responsible for the vehicle's actions. This is still new legal territory—states are writing rules about who pays when a self-driving car causes damage, and those rules vary.

If you are hit by a self-driving car, you would file a claim against the company's insurance, not the "driver." Your own insurance would handle it the same way they would if a commercial delivery vehicle hit you.

Safety Records and Real-World Performance

Self-driving cars have logged millions of test miles. Waymo reports that its robotaxis have driven over 20 million miles in testing and operation combined. Tesla reports that Autopilot-equipped cars have driven over 6 billion miles with the system engaged.

Comparing safety is difficult because the miles are not all in the same conditions. A robotaxi operating in sunny Phoenix on mapped routes faces different challenges than a Tesla on a snowy highway with a distracted driver. Some studies suggest that self-driving systems make fewer mistakes than human drivers in the conditions they are designed for, but human drivers are still better at handling the unexpected.

Accidents do happen. In 2023, a Cruise robotaxi in San Francisco struck a pedestrian who had been hit by another car moments before—the robotaxi did not cause the initial collision but failed to avoid the person in the road. Investigations into such incidents are ongoing, and safety standards are still being developed.

State and Federal Rules for Self-Driving Cars

The federal government has not yet written a single national standard for self-driving cars. The National Highway Traffic Safety Administration (NHTSA) has issued guidelines and is developing rules, but states are moving faster. California, Arizona, Pennsylvania, and others have already written their own rules for testing and operating robotaxis.

Rules vary widely. Some states require a human safety driver in the car during testing. Others allow fully driverless operation in defined zones. Some states require companies to report accidents and disengagements (moments when the human driver had to take over). Insurance requirements, liability caps, and data-sharing rules differ by state.

If you are considering buying a car with Level 2 features or using a robotaxi, check your state's current rules. They are changing—what is legal in California may not be legal in your state, and rules you read today may be outdated next year. Your state's Department of Motor Vehicles website will have the most current information.

What Self-Driving Cars Mean for Drivers and Passengers

For most people, self-driving technology will arrive gradually. Level 2 features are already in cars you can buy, and they will become more common. You will see more cars steering themselves on highways, but you will still need to pay attention and be ready to take over.

Robotaxis will expand to more cities, but they will not replace personal cars overnight. They work best for short urban trips where routes are predictable. Long-distance driving, rural areas, and bad weather will remain human-driver territory for years.

The biggest changes will be invisible to you at first: insurance companies adjusting rates based on safety data, cities redesigning streets to work with self-driving cars, and courts setting precedent for who pays when something goes wrong. These shifts are already underway.

Frequently Asked Questions

Can I use Autopilot or Super Cruise without paying attention to the road?

No. Level 2 systems like Tesla Autopilot and Cadillac Super Cruise require you to stay alert and ready to take control. The car can steer and manage speed, but you are still responsible for the vehicle. Taking your hands off the wheel or looking away for extended periods is dangerous and violates the system's terms of use.

Are self-driving cars safer than human drivers?

In the specific conditions they are designed for—highway driving in good weather, or robotaxis on mapped city routes—self-driving systems make fewer mistakes than average human drivers. But they struggle with unexpected situations, bad weather, and unusual road conditions. Overall safety depends on where and how they are used.

If a self-driving car hits me, who pays for the damage?

If a Level 2 car (like a Tesla) hits you, you would file a claim against the driver's insurance—the person owns the car and is responsible. If a Level 4 robotaxi hits you, you would file against the company's insurance. The rules are still being written in many states, so check your state's current law.

When will fully self-driving cars be available to buy?

No fully self-driving consumer car exists yet. Level 2 cars are available now. Level 4 robotaxis are operating in a few cities but are not for sale. A true Level 5 car (no steering wheel, no pedals, works anywhere) is still years away, and when it arrives, it will likely be expensive at first.

Do I need special insurance if my car has self-driving features?

Your regular auto insurance covers a car with Level 2 features. Some insurance companies offer discounts if your car has safety technology. If you use a robotaxi service, the company's insurance covers the ride—you do not need to buy anything extra.