Why does a car feel floaty at high speeds?

[LeReid]

Reasons why a car feels floaty at high speeds: There is a significant change in lateral airflow forces. For example, when overtaking at high speed, a small car and a large vehicle overtaking side by side will make the small car feel more floaty. This is because when overtaking, the airflow channel between the two vehicles narrows, the flow velocity increases, and the air pressure decreases, creating suction. During high-speed driving, the car needs to break through the air resistance barrier in front. The dispersed air flows relatively over various surfaces of the car body. When passing surfaces of different shapes, since the volume of air flowing is equal, the airflow speed above the car will be greater than that below the car. The pressure difference between the air above and below the car creates a certain "lift force," which reduces the tire grip and thus decreases the stability of the car at high speeds.

[FelixMarie]

I've got plenty of experience with high-speed instability. First is the vehicle's weight – especially the huge difference between fully loaded and empty. A packed trunk makes it much more stable. Second comes the tires – overinflated pressure or worn tread patterns can drastically reduce grip. Third is suspension stiffness – I've driven cars with soft suspension tuning where the steering wheel would shake when crossing bridges in crosswinds. Fourth is ground clearance – that's why SUVs are more prone to instability than sedans. Lastly, older cars with excessive steering system play require constant minor corrections at 120 km/h – my arms would ache after one highway trip. Oh, and body design matters too – some cars generate excessive underbody turbulence with insufficient downforce, making the rear noticeably wobble during overtaking.

[Brynlee]

Last time I drove my friend's modified car, I truly understood the importance of aerodynamic kits. Stock cars tend to feel floaty at high speeds mostly due to turbulent airflow—chaotic underbody airflow can lift the chassis, causing a drastic loss of grip. Hatchbacks without rear spoilers are at an even greater disadvantage, as the rear wheels can't maintain enough downforce, leading to a drifting sensation. Worn suspension bushings are another culprit—I've personally seen a car transform from unstable to rock-solid in corners after a shop replaced its cracked suspension bushings. Also, don't cheap out on tires: a colleague switched to some no-name brand, and above 100 km/h it felt like driving on cotton. Recently discovered a pro tip: during maintenance, ask your mechanic to prioritize checking chassis bushings—when rubber components wear out, the whole car starts feeling floaty.

[PenelopeMarie]

Three key points: vehicle weight, airflow, and suspension. Lightweight cars are prone to swaying in crosswind areas; the absence of underbody deflectors increases lift; and suspension wear can lead to inadequate body support. Tires also become harder over time, making the car more likely to drift. Older cars with significant steering wheel play require extra caution. To improve, prioritize switching to tires with strong grip and maintain tire pressure according to the manufacturer's standards. It's recommended to keep the vehicle's weight balanced on both sides—many people don't realize that loading luggage on one side can affect dynamic balance.