Car features Parking sensors

Parking sensors are the cheapest parking systems

As parking spaces get smaller and ever harder to find, the once-simple act of parking has become the bane of the modern motorist's life.

The average car is now longer, wider and taller than ever before, and those plunging, pedestrian-friendly bonnets and wide, safety-conscious roof pillars limit all-round visibility.

Yes, alloy wheels and painted bumpers look much smarter, but scuff or dent them and your wallet will suffer the consequences.

With prices starting at just £30, it’s therefore hardly surprising that parking sensors, rear-view cameras and automatic parking systems have taken off. These systems take the stress and guesswork out of parking and could potentially save you an expensive repair bill or insurance claim.

We take a closer look at the different types of parking systems and how they work.

The simplest kind of parking aid, parking sensors, comes in two varieties:

Ultrasonic parking sensors

Ultrasonic sensors bounce sound waves off obstacles, using the ‘echo’ time to indicate how far away they are. A speaker in the car bleeps – increasingly frantically – as they get closer.

Pros of ultrasonic parking sensors

The cheapest form of parking aid – aftermarket systems cost as little as £30; car manufacturers charge £300-£700.
Sensors detect objects even when the car is stationary.

Cons of ultrasonic parking sensors

Ultrasonic sensors can miss smaller or narrow objects, and inclines can deflect the sound waves – a steep ramp, for example.
They also only detect objects directly behind or in front of the car, and may not work if the sensors are dirty or out of alignment.
Fitting usually requires drilling the bumper, but stick-on sensors are available (though unattractive).
Ultrasonic parking sensors not be suitable for use with a tow bar.

Electromagnetic parking sensors

Electromagnetic parking sensors create an invisible electromagnetic field around the car’s bumper; any objects entering it trigger a warning sound. Currently used by Audi, Citroën and Fiat, among others.

Pros of electromagnetic parking sensors

Suitable for use with tow bars, cycle racks, etc.
Electromagnetic sensors are mounted inside the bumper, so there's no need for drilling.

Cons of electromagnetic parking sensors

Electronic parking sensors are more expensive – prices start from £70 (aftermarket). The factory-fitted cost is about the same as ultrasonic sensors, however, at £300 plus.
Electromagnetic sensors only detect objects once the car has started moving.