Car Tech A to Z: O is for odometer and occupant sensors

The technology contained within the modern motor car can be both fascinating and slightly baffling. Most such technology exists to make our cars safer, more efficient and just better than ever to drive but some of it can be quite confusing for the average motorist. In this A to Z series we will attempt to unravel the mystery of technology that is the modern motor car. This week, we’re visiting the letter O…

O is for…odometer. Also known as a mileometer, an odometer is simply a device that measures how far you’ve travelled and it’s thought to have been invented as long ago as 287bc by Archimedes of Syracuse.

An odometer can be either digital or mechanical, although in most modern cars the odometer works electronically by simply logging vehicle speed and then calculating the distance travelled.

O is for…occupant sensors. Fitted to all modern cars, occupant sensors determine whether a seat is unoccupied or not and, in some cases, not only asks a passenger to put a seatbelt on, but also works in conjunction with the airbag system to establish how heavy an occupant is – to then work out how far and how fast to deploy the airbags in the event of an accident.

The system consists of a weight sensing pressure pad mounted beneath the front passenger seat – a set belt tension sensor – a small ECU that runs the system beneath the front passenger seat – and an airbag status indicator lamp, mounted in the roof console.

Thanks to occupant sensor systems, never before have we been so safe when travelling in our cars.

Next, the letter P...