Super Light-Weight (Super LIGHT-Car) Car Research and Development

A consortium of 38 leading organizations with Volkswagen serving as a project coordinator initiated the super LIGHT-Car (SLC) project in 2005. It was co-funded by the European Commission under the 6^th Framework Programme, and was part of the European Council for Automotive Research’s (EUCAR) multi-material development efforts. The main aim of SLC was the development of a multi-material, real, C-class body structure (BIW) that achieved a 30% weight reduction, compared to the 2005 benchmark vehicles.

Other goals were reduced material consumption, lightweighting costs of no more than 5 €/kg, equivalent structural performance, and the capability of being produced at a rate of 1,000 vehicles per day.

During the project’s second year, three new vehicle concepts were developed each having a different focus. The first was the universal light body concept (ULBC), which focused on all of the original project goals, but with a cost requirement (< 2.5 €/kg) even lesser than the original goal set for the project.

This effort caused a 29% mass reduction of 82 kg, at an additional cost of 2,7 €/kg. The second was the super light body concept (SLBC). Here the focus was on maximizing weight saving, with a more generous cost requirement of < 10 €/kg savings. This resulted in a mass reduction of 41%, or 114 kg, with a cost increase of 2,70 €/kg. ArcelorMittal, one of the SLC partners developed the third concept, one of the SLC partners, whose all-steel efforts focused achieving cost-effective weight reduction through the utilization of the latest grades of steel.

Combining these designs into one, the Super LIGHT Car uses a wide range of materials that includes:

• 53% aluminium,
• 36% steel (in a variety of grades),
• 7% magnesium, and
• 4% composite

Material distribution for SLC is shown below.

Figure 1. Super LIGHT Car material distribution.

A cost analysis is included in the SLC study but did not have a life cycle assessment (LCA). The analysis showed that the cost to produce SLC was 112% of the reference vehicle, a Golf V. Differently stated the cost of light-weighting was more than 7 €/kg.

LCA of the body structure was done by Volkswagen and PE International, but appear to have apportioned use phase savings based on the weight savings from the multi-material approach.

This has to the potential of greatly exaggerating use phase savings; indeed, they concluded that use phase savings more than offset the high production emissions, and noted that “recycling credits for magnesium and aluminium were higher than the steel reference vehicle”.

Life Cycle Assessment Parameters

WorldAutoSteel conducted a vehicle life cycle assessment (LCA) comparing the SLC to a Volkswagen Golf V as the baseline vehicle, and a simulated Golf V manufactured from AHSS.

The University of California at Santa Barbara (UCSB) GHG Materials Comparison Model, featuring the most up-to-date LCI’s for steel (worldsteel, 2010) and aluminium (IAI, 2005) was used. The vehicle analysis included an estimated lifetime mileage of 200,000 km and fuel consumption ratings of 7.2 L/100km or 32.7 mpg, Golf V performance with a 1.6 l gasoline ICE. All evaluations were done with a recycling treatment consistent with end-of-life methodology and the prescription adopted by the metals industry (alpha value = 0.1). This treatment is suitable for materials having high manufacturing emissions. The modelling parameters are shown in Table 1.

Table 1. UCSB Model Parameters for Super LIGHT Car

AHSS Mass Reduction Potential

The UltraLight Family of Research and industry practice, shows that a 25% mass reduction can be achieved with AHSS when compared to conventional mild steel. Optimisation techniques have yielded light weighting potential beyond 35% for specific sub-systems. In the AHSS-intensive Golf V concept mass reduction potential of 20% has been estimated when compared to the baseline vehicle, recognizing the potential of optimisation and the reality of a body structure already using some AHSS products.

The Table 2 below shows the results of the UCSB modelling.

Table 2. UCSB GHG Materials Comparison Model Results for Super LIGHT Car

Conclusions

Multi-material vehicles have distinct emissions advantages in the use phase, but distinct disadvantages in the production phase. Figure 2 shows that with optimal recycling behavior, Super LIGHT Car achieves slightly lower life cycle emissions compared to the AHSS-intensive concept.

Figure 2. Tailpipe vs. Total Life Cycle Emissions for Super LIGHT Car.

SuperLIGHT car’s production emissions account for around 12% of its lifetime emissions and cannot be ignored while considering environmental impacts contrary to the misperception that material production emissions are insignificant.

The AHSS-intensive Golf V concept is the only design or material solution that results in mass, cost and emission savings in all life cycle phases, compared to the baseline design.

Super LIGHT Car (or multi-material vehicle), results in 65% greater production emissions compared to the AHSS-intensive concept vehicle. Accumulative emissions are hence significantly greater until recycling occurs at vehicle end-of-life. Super LIGHT Car shows 650 kg greater CO2e per vehicle compared to the AHSS-intensive concept. With an assumption of 15 million vehicles in production by 2015, this accounts for approximately 10 million additional tons of CO2e annual emissions.

Research studies argue that upfront emissions cause more damage to the environment due to cumulative radiative forcing (CRF) and propose the application of a time correction factor (TCF) to account for such temporal effects. American Iron and Steel Institute (AISI) and Unversity of California-Davis collaborated on a study whose results emphasize the need for LCA and CRF cumulative effects to prevent tailpipe emissions legislation that cause unintended consequences. This is shown in Figure 3, which is a chart with TCF’s applied to the material production and recycling phases of the total vehicle life cycle. The results show the difficulty in recovering from the harmful emissions associated with environmentally unfriendly materials.

Figure 3. The Application of Time Correction Factors to Production Emissions

This information has been sourced, reviewed and adapted from materials provided by WorldAutoSteel (World Auto Steel).

For more information on this source, please visit WorldAutoSteel (World Auto Steel).