The i3, BMW claims, is revolutionising vehicle production, using a modular design, likened to a Lego system that makes it far easier to assemble and, in turn, to repair sections of the car separately - for example, a door panel. That door panel will be made out of carbon-fibre plastic, which largely replaces steel and aluminium as the material of choice for the outer body, a move that will be extended to other BMW models in the future. Proving its worth with its light weight and safety potential in the competitive world of Formula One, carbon fibre does not suffer from corrosion, making rust a thing of the past. It's also very resistant, hence its popular use in the aviation industry, and "offers freedom in terms of design and tailor-made characteristics", says BMW. Finally, its lightness means it counters the heavy battery in the i3, helping to reduce the overall weight of the car, which is vital for BMW to keep its reputation for driving dynamics throughout the electric range.