Around 30 years ago, the kerb weight of a basic Japanese everyman’s car was around 1000 kilograms. I would know, because the car I pedal around with on a daily basis is 30 years old, and it’s quite nearly as light as a Lotus, though it doesn’t quite have the power to match. Even up until the early 2000s, Japanese cars managed to maintain low kerb weights, which in turn helped with things like fuel efficiency and handling ability.
But naturally, the light weight came at a cost. It’s not as if these companies had widespread access to exotic materials like carbon fibre or high strength aluminium No, these cars were still made of standard steel- and thin gauge at that- which meant that the body structures of these cars weren’t the strongest things in the world. European cars like the Volvo 240 GL were heavy and bulky, but they were built like tanks and were near impossible to destroy.
The increased focus on crash protection and the legislation from numerous countries has forced car manufacturers to improve the structural safety of their models. In addition to redesigning the chassis for better load paths and more efficient crumple zones, companies need to add more material to maintain the rigidity of the car. Rigidity and torsional rigidity is something you hear car companies brag about with every new model generation, usually for sports cars- it simply refers to how well the chassis holds it’s shape under high stresses and loading.
All of this extra engineering adds weight. It packs on the pounds, and generation by generation, you’ve put on an extra 400 kilograms. Removing weight is far more difficult than adding weight, which is also why most European manufacturers shout about it if they succeed. In addition to the extra material used for the chassis, a fair amount of the weight comes from things like sound deadening and various interior options. Those electric seats that you so dearly need? An extra 40 kilograms a piece, courtesy of the motors and other various components.
So while cars have gotten fatter, and heavier, and bulkier, there is always solid reasoning behind it. Occasionally the weight drops, through some radical new manufacturing technique or metallurgical process, but in general kerb weights will only rise. At the end of the day you can’t fight physics, and unless customers are willing to pay the premium for exotic materials for their cars, the weight is likely to go up with each successive generation.
