When Audi revealed the lightweight engineering behind the next-generation Audi A8 recently, the punchline came as a surprise.

The bare bodyshell of the new car, which Audi has thrown its considerable expertise in lightweight engineering at, is actually 51kg heavier than that of the outgoing model. So what’s going on?

Producing cars is a process of addition and subtraction. Reducing the weight is crucial because it takes less energy to move a lighter car, and therefore fuel consumption can be improved. On the flipside, manufacturers are forced to put weight back in to their new vehicles. Who is to blame for that? Well, in part it is due to legislators and ever-evolving crash safety standards, but we, the car buyers, have to shoulder some of the blame too.

There are three main reasons why cars gain weight. One is equipment. Manufacturers tell us that customers demand more and more gadgets in the car, all of which add weight. More sophisticated climate systems, infotainment, connected car technology, thicker glass, multi-function electric seats, air suspension, bigger wheels than ever before - you name it, this stuff all adds lots of weight.