Toyota's ES3 concept uses plants such a sweet potato as raw material for its plastics, rather than petroleum

Between eight and nine million vehicles are scrapped each year in Europe, representing more than eight million tonnes of waste and a potential source of soil and groundwater contamination.

Around 75% of the average vehicle weight is currently recycled through metal recovery. The majority of the remaining components, especially rubber and plastics, are still disposed of as shredder residue. The main reason for this is the high cost of dismantling, logistics and recycling.

Recycling rates vary from country to country, once again due to differences in the recovery market, costs and the quality of treatment processes. These factors highlight the necessity of matching the early stages of design for recycling with current economically sustainable practices.

Car design engineers are striving to limit the diversity of materials used with a view to ensuring that individual components should be manufactured from so-called pure-sorted materials. For composite constructions, investigations are being made for materials that are compatible in a joint recycling process.

As regulations which will make manufacturers responsible for dealing with ‘end-of-life’ car elements take effect, manufacturers are also developing systems to ensure that operating fluids are quickly segregated and collected for subsequent recovery. Components containing hazardous materials, such as batteries and airbags, are also being designed for easy dismantling.

A consortium of more than 20 car manufacturers has formed to provide dismantling information in electronic format – the International Dismantling Information System (IDIS). This is updated regularly and distributed to the authorised dismantling network in each European member state.

The likely increase in hybrid cars for the medium term means that large batteries disposal will become a more important concern. Hybrid leader Toyota has established a dedicated Ni-MH battery recycling network for the collection and disposal of its Prius model batteries, reckoned to have a life of about five years. In all countries where Prius is sold roadside assistance and emergency services have been informed on how to handle batteries in case of a vehicle breakdown or accident.

Finding substitute materials to reduce hazardous chemicals remains a challenge for design engineers who must also guarantee product quality. The wire electrical harness, which traditionally required lead for heat resistance, uses an alternative material in an increasing number of new cars. The radiator, heater core, fuel hose and fuel tank are also becoming lead free components.

Recyclable plastic materials are now being increasingly developed and used used in new cars. Toyota, for instance, recycles waste in its European plants derived from the production of plastic parts internally and uses the material to produce new bumpers.

Technology to sort and extract polyurethane foam and fabric granules from scrapped car shredder residue has also been developed, and this material is recycled to make components for new vehicles such as sound-proof mats.

Even non-plastic and non-metal materials used in car production is changing. One example is the introduction of Kenaf as a replacement of wood pulp, for package tray trim and other parts. Kenaf material is made with the fibres of one-year old Kenaf grass as a replacement for wood-derivatives.

Concept cars are often used to demonstrate the use of biodegradable materials. Plastic trim in the Toyota ES3 concept uses plants such a sweet potato as raw material for its manufacture, rather than petroleum.