An Australian peer-to-peer car rental company will install GPS devices in some of its vehicles to ensure that the vehicles are safe, but a civil liberties group complains the devices intrude on drivers' privacy.

DriveMyCar Rentals, a company with more than 5000 registered users across Australia, will initially install the devices in up to 30 percent of its fleet. The devices will allow the company to track the location of the vehicle in real time and to be notified by when travellers breach the terms of their rental agreement, such as driving on dirt roads or out of city areas.

The company states it is installing the devices to give "peace of mind to the vehicles' owners." Daniel Noble, CEO of DriveMyCar Rentals, said owners "want to know that their cars are safe."

However Civil Liberties Australia (CLA) said the installation of GPS units and the tracking of renters is an "excessive invasion of privacy." CLA Director Tim Vines said that after providing a photo identification, a deposit, and providing credit card information, drivers are now being told that still isn't enough. Now, they have to be tagged and monitored, he complained.

The device, plugged in to the car in either the boot or the center compartment, will send the GPS coordinates back to the company and will be used in conditions such as non-payment, if the renter cannot be reached for a period of at least two weeks, or if the owner is concerned about the car's location, such as a flood-affected area. It will also be used to make sure travellers aren't breaking the conditions of use by venturing into restricted areas, and they can be penalized for doing so.

A consumer advocacy group says the use of the GPS device to fine renters who breach agreements seemed excessive and added the systems might not always provide accurate information. CLA director Vines has also questioned the security of the information. But Noble said that the company uses fully encrypted servers, and the information is only available in real-time and is not stored for later use. Renters will be alerted to the presence of the devices in the Web site's terms and conditions as well as the rental agreement itself and with a sticker on the car's window.