SENSOR SYSTEMS
Parking only

Camera systems
Safety or parking

WIDE-Angle lens
Safety or parking

Detect objects behind the vehicle and use beeping or flashing signals to tell the driver how close they are.

Pros Automatically alerts the driver when objects are near or if something has moved behind the car. Less expensive than cameras.

Cons Driver can’t see behind vehicle. Most won't sense smaller or low objects in path. Ultrasonic models don’t work well in bad weather. Microwave models don’t detect objects if vehicle and object are stationary.

Price $275 to $395.

When the vehicle is in reverse, a small camera sends an image to a video screen that gives the driver a wide-angle view of the area behind the vehicle.

Pros Allows the driver to see people, animals, and objects that might otherwise be hidden in the vehicle’s rear blind spot.

Cons Pricey. No active warning system; camera systems are effective only if the driver looks at the display while backing up. Some have poor night vision images.

Price $150 to $800.

Sticks to the rear window and helps shrink the vehicle’s rear blind spot.

Pros Inexpensive. Easy to install.

Cons Details are hard to see. Lens still leaves a sizable blind spot. Effective use is limited to vehicles with a near-vertical rear window. Can interfere with normal visibility.

Price $20.