The weight reductions in railway vehicles attainable through the use of fibre-reinforced plastics obviously depend on the share of the vehicle mass replaced by these materials and thus on the application context.

According to estimates of the Rocky Mountain Institute, weight reductions through the use of fibre-reinforced plastics may be up to 65% in the automotive industry (Pehnt 2001). This is obviously very optimistic and not as such transferable to railway conditions.

The energy efficiency through weight reductions could be compensated by the high energy demand in the production phase of fibre-reinforced polymers.

Estimates made by DLR (Deutsches Zentrum für Luft- und Raumfahrt) for automotive applications indicate that the life cycle net result of higher energy demand in production but higher energy efficiency during use may be close to zero. The concrete outcome depends on many factors such as product life, recycling strategy etc. (Pehnt 2001).

• Recycling properties are generally worse than for metals due to heterogeneity of material.
• Fibre reinforced materials often contain toxic or at least problematic chemicals especially those composites equipped with fire retardants.