One surefire way to lower the weight of your car is to give it a carbonfibre tub, a la Alfa Romeo 4C. Since these are shockingly expensive to make, some manufacturers are going for the recycled option. It’s a material we first heard about in the Zenos E10, however it’s since been revealed that the same stuff is used to make the passenger compartments of the BMW i3 and i8.
It utilises carbonfibre offcuts, which are smashed into tiny pieces and laid out into sheets. These sheets are then bonded together with thermoplastic, resulting in a light material that has 70 per cent of the tensile strength of ‘virgin’ carbonfibre, but can be produced at just 10 per cent of the cost.
If a harder, more focused version of a sports car is to be produced, an easy way to cut the weight figure down is to simply get rid of some luxuries. Take the Porsche Boxster Spyder, for example. It shirks an electric roof for a simpler manual version, and there’s no air conditioning or stereo as standard.
Probably the most anal approach to weight savings is to employ something like Mazda’s ‘Gram Strategy’. Rather than getting rid of a load of luxuries or making bits of the car out of unobtainium, this is a much more simple - albeit very thorough - approach first used by the Japanese manufacturer for the NC MX-5, and later the ND (pictured above).
Mazda look at every single component, and if it could be redesigned to save weight, it is. In the NC, substantial weight reductions were made from the body, chassis and engine, but the more interesting changes were much smaller.
A plethora of components were re-designed - screws were shortened, interior parts reduced in complexity, pieces made from a different material - and it all added up. Hell, the engineers even saw fit to shave eight grammes off the rear-view mirror. For the NC, all of this resulted in 100kg shed. Not bad.
Traditionally, suspension springs are made of heavy steel. But do they have to be? Not necessarily. Both Ford and Audi have been going down the path of making composite springs, with the latter manufacturer now actually sells its A6 Avant TDI Ultra model with glass fiber-reinforced polymer coils at the rear, something which will also make an appearance on the R8 E-Tron. This saves a total of 2.2kg compared to steel springs. Not a huge amount of weight, but as we’ve seen from Mazda’s strategy, a lot of small changes amount to a big reduction.
We’re still in the early days of carbonfibre wheel manufacturing, but it probably won’t be too long before the use of CF rims becomes widespread, particularly with performance cars. Why? Because the benefits extend far beyond reducing the overall weight figure. By reducing the rotational mass of the wheels, the suspension doesn’t have to work as hard, and the wheel will be in full contact with the tarmac for more of the time. Also, there is the potential for small improvements in acceleration, as it’s easier for an engine to rotate lighter wheels.
Once upon a time, only the most exotic cars came with any notable amounts of aluminium and/or carbonfibre in their construction. However, it’s now becoming a lot more common. Take the new Alfa Romeo Giulia, for instance. The suspension arms, engines, doors and wings are all made from the stuff. On the hot QV model, the bonnet and roof are carbonfibre, and every single model - even the boggo spec diesels - will feature a carbonfibre prop shaft.