FACTBOX-Some facts about aluminium and steel in cars

(Reuters) - The push for lighter cars as environmental pressures intensify could benefit aluminium, given it is lighter than its competitive material steel.

A major challenge facing the auto sector is European Union regulations, which stipulate CO2 emissions from an average car must fall to 130 grammes/km by 2015 from 144 grammes/km in 2009.

But steel companies are developing lighter, stronger steels in a bid to retain their dominance.

Below are some facts about aluminium and steel use in cars.

ALUMINIUM

* Cars have been increasing in weight since the 1970s when the average vehicle weighed about 800 kg. The average weight is now around 1300 kg, with aluminium accounting for around 10 percent.

* A lighter car lowers fuel consumption and carbon dioxide emissions -- the main impetus behind calls for the metal’s more widespread use.

Every 100 kg of weight saved equates to lower emissions of 9 grammes CO2/km and 0.35l/100 km less fuel used.

* In 2000, Britain produced around 1.64 million cars, containing around 105 kg of aluminium. In 2009 about 1.0 million cars were produced containing approximately 140 kg of aluminium, according to Britain’s Aluminium Federation (Alfed). Aluminium is now used for bonnets and tailgates on numerous models and for doors on some makes.

* Based on 2008 figures of 132 kg of aluminium in a car, Alfed says:

26 kg in bonnets/doors, front structure, bumper beams

37 kg in wheels, suspension arms, steering system

69 kg in the engine block/cylinder head, transmission housings, radiators * The thickness of a car body panel has to be increased by one-third when using aluminium to get the same strength as steel, Alfed said. But in general, the aluminium part will be 30-50 percent lighter than one made from steel.

* The average car weighs about 1300 kg. If there were no commercial limitations and as much aluminium as possible was used, it would weigh about 775 kg, Alfed estimates.

* Aluminium castings are used in engines, cylinder heads and blocks, gear housings, brackets and pump bodies.

Aluminium extrusions are used in bumpers, the sub-frame for the Audi A8 as well as other body components.

Aluminium rolled sheet is used in car body panels.

Glass reinforced plastics are a competitor to both aluminium and steel in car body panels.

* Aluminium car bodies are confined to luxury vehicles. Aside from the Audi A8, other cars which have aluminium bodies are Jaguar Land Rover’s XJ and XK models.

The body shell of the Jaguar XJ weighs just under 300 kg, comprising over 95 percent aluminium, the company said.

For an interview with Jaguar Land Rover (JLR), owned by India's Tata Motors TAMO.BO on the potential growth of aluminium use in cars.

Daimler's DAIGn.DE Mercedes-Benz said aluminium will be used for outer panels because the potential to reduce weight with high strength steels is limited for these parts because of the minimum sheet thickness required to ensure stiffness.

The company said decisions on the use of different materials (including substitution) are driven by a variety of factors, many of which are of technical nature.

Price stability is an important factor which needs to be considered for all materials, it added.

STEEL

* Steel is used generally in body, closures, powertrain, engine, tyres and suspension components.

* The automotive sector accounts for around 16 percent of total steel use in the European Union (EU).

* Downsizing in engine technology would have an impact on steel usage in autos in coming years, according to the German Steel Federation. It said higher specific engine performance would lead to the use of an increasing amount of heat resisting steels.

* Approximately 840 kg steel are in an average compact car, equivalent to 60 percent of the total weight.

* The main competitive materials for steel are as follows:

Car body: aluminium, magnesium, fibre reinforced plastics

Powertrain: aluminium, magnesium

Suspension: aluminium

The above mentioned competitive materials are used for weight reduction, if component costs are of minor importance, according to the German Steel Federation.

* The push for lower fuel consumption and carbon dioxide emissions would lead to an increase in the amount of high-strength steels used, it said.

“No exact prognosis possible, due to competition of materials, manufacturing technologies and design,” the German Steel Federation said.

* Mercedes-Benz said it uses a significant amount of steel in various types and forms per year.

In terms of trends in steel use it saw the following:

- decreasing application of mild steel

- increasing application of Advanced High Strength Steel, Ultra High Strength Steel and Press Hardened Steel

- additional influences from increased use of aluminium and limited potential to decrease the thickness of the parts (loss of stiffness)

- in the mid-term future, further progress expected in terms of weight reduction with steels having less density.

* WorldAutoSteel in a recent publication said the production of one kg of conventional steel or advanced high-strength steel generates between 2.0 and 2.5 kgs of CO2 on average.

In contrast, one kg of aluminium creates between 11.2 and 12.6 kg of CO2.

"An erroneous perception has emerged that lighter autos and reduced emissions are primarily associated with the application of low-density materials, like aluminium, magnesium and plastics," Brian Aranha, chief marketing officer for the automotive sector at ArcelorMittal ISPA.AS said in a recent interview.

* Old steel from a car produced 10-20 years ago can be recycled and turned into new steel grades with improved properties, according to Corus, the European arm of India's Tata Steel TISC.BO, in a recent interview.