When 100 kg still meant one liter of consumption
08/02/2019
Many of us will remember this. In the seventies and a little before and after, the rule was that a car needed about one liter of petrol per 100 km for every 100 kg of weight. That was pretty much true, because a Citroën 2 CV needed about 6 liters per 100 km, a VW Golf 8 liters, and a full-grown Ford Taunus perhaps 10 to 12 liters. The rule also applied to additional weight. So if you took the whole family and their luggage with you on vacation, the sedan quickly swallowed 2 or even 3 liters more per 100 km.
Of course, this was only a rough rule, but with most of my cars at the time, the deviation over long series of measurements was relatively small. Test consumption was often higher because the driving was much harder and more fuel-intensive. If you really wanted to save money, you could get significantly less than one liter per 100 kg. And of course it also depended on the vehicle (including aerodynamics) and the technology, because there were much greater differences back then than there are today.
Engineers have done a lot of work since then. Ten or 15 years ago, people were already talking about 0.3 liters per 100 kg that would be burned per 100 km. And today, the additional 100 km consumption per 100 kg is perhaps even lower. This is also reflected in everyday life, as modern cars can usually be driven quickly with 5 to 8 liters, even though they weigh 1500 to 2000 kg.
The extra weight that our modern cars carry around is often justified by the additional safety. However, this is only partly true, as the bodies have not actually become that much heavier. In some cases, they have even become lighter thanks to high-strength steel and the use of lightweight materials. The additional weight has more to do with ever larger cars and, above all, much higher demands on comfort. In addition, a car with 400 hp naturally has to have completely different brakes on board and larger wheels on the axles than a car with just 80 hp, as was usually the case 40 or 50 years ago.
