Toyota is testing a system that would allow the Japanese company's electric cars to automatically top up their batteries every time they are positioned over a charging coil in the road.

Toyota wants to make recharging an electric car as simple as parking and so is examining resonance charging systems in the hopes of offering the feature in the near future.

Unlike other wireless charging technologies, systems that use magnetic resonance don't need to make physical contact with a battery in order to charge it and can therefore top up a car's batteries over a short distance.

Toyota's plan is to fit recharging coils under parking spaces and then to tweak its existing parking assist technology to ensure that any compatible car is optimally positioned over the coil when it stops.

A small test program is currently underway in Japan using three plug-in hybrid cars, and Toyota will assess the results and levels of user satisfaction before making a decision regarding commercialization.

Fellow Japanese carmaker and electric vehicle pioneer Nissan has been developing a similar technology for its line of LEAF all-electric cars since 2011. It is also investigating the feasibility of building wireless charging points along major highways that would continually charge electric vehicles as they traveled.

So far the only stretch of road capable of automatically charging electric vehicles as they drive by is in South Korea and is used for powering two buses. It went live in August 2013.