Ground clearance over time: “Chassis got low low low low low low low low”
What is the single most prominent trait of a car that differentiates modern cars from vintage ones? Some may say aerodynamic design, the use of electronics, or engine power. I would say ground clearance or ride height distinguishes a modern car from an old one the best. Cars are getting lower, and an ordinary chassis height from the old time would be considered high above today.
Let’s talk about the body structure first. A car consists of mainly two parts: the cabin and the chassis. At the beginning of the automobile era, the cabin is the place to sit and drive and is built “on” the chassis. As for the chassis, a strong ladder frame holds the suspension, engine, and transaxle and carries the cabin on top. We call this “body-on-frame”, and it is still used by some heavy-duty off-road vehicles and trucks today. Body-on-frame provides better strength but is heavier due to the additional chassis frame. Since the cabin is located above the frame, the ground clearance could not be lower than the frame itself.
In contrast to the body-on-frame, the uni-body design is lighter and provides the possibility for lower ground clearance. It requires more complex welding techniques and better material quality, so it only became popular after the wars. Most sedans and even crossovers today adapt the uni-body design. The chassis and cabin are combined into a single piece, and the power train is hung onto the body. People still use the term chassis today, but now it only refers to the power train and the axles.
The story of ground clearance does not end with the introduction of uni-body. The uni-body vehicles from the 1960s would still be quite high today. Some sports cars of the last century have a ground clearance higher than today’s city cars. Jaguar E-Type was the icon of its era, and would still be sleek and elegant today. It had a low roof, but the ground clearance was still high compared to its successor F-Type.
Several factors contribute to the trend. The first one is road quality, which is an approximate index of the infrastructure progress. As the high-quality roads expand even to the wild, chances are low that one would encounter a bumpy rocky road. For an on-road cruiser, ground clearance could be reduced in return for a better driving experience.
That brings the second factor: the pursuit of performance and aerodynamics. A lower floor often comes with a higher handling limit, and that is why car tuning often includes a lower suspension setting. As the floor is lowered, the height of the vehicle can be lower in return for better looking, less drag, and more silence in the cabin. This is why some luxury sedans are getting lower over the generations without compromising the space.
Still, in some Southeast Asian and Latin American countries, roads are not as good as those in Western countries, and thus people need higher vehicles. In the past, however, customers had the only sedan to choose from, so those old sedans had to be high enough. With the recent rise of SUVs and crossovers, manufacturers can differentiate the target customers by setting different ground clearances for SUVs and sedans. Sedans can be as low as possible now since customers in need of higher ground clearance can always choose an SUV. Sales figures also show that the need for versatile utility vehicles is growing in these markets.
So the third factor is that manufacturers use ground clearance as a key differentiation for different products. Most sedans and even urban crossovers that are not designed for the wild are having low heights today. The BMW X2 would be like a dwarf compared to the Model T even though it is classified as an SUV today. A BMW 4-Series would be the supercar in the 1950s in terms of ground clearance. As for the sports car, they push the limit even forward. Driving a Ferrari today would be like skating on the ground.
