In every magazine, somewhere in a test or a press release, you will find the statement that the car is X per cent stiffer than the previous model. This is either because of a redesigned structure or high-strength steel that has been used in the construction.
1. Is there a way to prove this statement, or test it? Can the body be tensioned and the amount of force be measured?
2. If this statement is true, how should I feel when I drive an older model? Is my car now as soft as a rubber duck in comparison? Should I feel unsafe because new cars are so much stiffer?
JOACHIM SCHIFFER – Windhoek
We wholeheartedly agree with you. Some time ago, we questioned the suspicious claims of increases in torsional stiffness at a new model launch, but all we got was a shrug from the marketing manager.
The marketing people are always on the lookout for advances that they can trumpet to mostly technologically ignorant motoring journalists. On a percentage basis, most of these improved stiffness values mean very little, so you need not worry when driving an older car.
The stiffness can only be measured on a barebody/ floorpan shell by clamping one end down, applying a torque to the other end and measuring the deflection in kilo-newtons per degree.
However, it’s interesting to note that there is usually a noticeable difference in stiffness between a one-tonne bakkie, which has a separate chassis, and a modern saloon whose body/floorpan is welded together. While travelling on a bumpy road, the bakkie will flex noticeably but the saloon will feel far more solid.