Your car would be unbearable to drive without its suspension. Youd likely need a chiropractic appointment by the time you made it out of your neighborhood. Not only does a suspension support (or suspend) the weight of a vehicle, it keeps body movements under control when you hit a bump and improves ride quality by isolating the vehicle from road imperfections. Load-bearing duty typically falls on steel or composite coil or leaf springs, but there are better solutions. What if instead of riding on flexible metal or plastic, a vehicle could be riding on air? How Do Air Suspensions Work? In the case of an air-suspended vehicle, those coil springs or leaf springs are swapped for pressurized flexible rubber bellows called air springs. An air spring at each corner is monitored by the vehicle for internal air pressure and ride height. With help from an onboard compressor, air dryer, and air reservoir, the air pressure (which determines the equivalent spring rate) and ride height can be adjusted to provide optimal ride quality and ground clearance for the task at hand. The idea for air suspension has been around nearly as long as the automobile; a Pneumatic Spring for Vehicles was patented in 1901. It was utilized by the U.S. military in World War II on heavy trucks to maintain ride height independent of vehicle load. By the late 1950s, air suspension was standard equipment on the Cadillac Eldorado Brougham, and today the tech is near ubiquitous on high-end luxury cars. Air Suspension: Pros and Cons Most of the advantages of equipping a car with air suspension relate to adjustability. By increasing or decreasing the volume of air in the spring, an air suspension system can raise or lower a vehicles ride height and consequent ground clearance in seconds, which has myriad benefits. The first is improving off-road capability. Countless SUVs, from the Mercedes-Benz GLS to the Lamborghini Urus and Jaguar I-Pace, utilize air suspension to increase ground clearance and improve approach, breakover, and departure angles. Raising the suspension reduces the likelihood of a vehicle getting stuck off-road or taking underbody damage from hazards on the trail. There are also benefits that come with lowering the suspension. If youve ever climbed into or out of a lifted truck or SUV, you know what were talking about. Even our long-term Jeep Wrangler Rubicons drivers seat is something of a boar to clamber up to, so a vehicle on air suspension that can crouch down to ease ingress and egress (picture the kneeling public transit busses) is a real luxury. Having a car sucked down toward the ground has fuel economy benefits, too. Lowering a car decreases its frontal area, which has a positive impact on its overall wind resistance or drag area (the product of frontal area times coefficient of drag). Less drag means less fuel to accomplish the same amount of work, which can save you cash. Air suspension also plays nicely with predictive suspension systems that read the road with cameras to detect upcoming pavement imperfections. Weve seen this kind of system used to great effect in cars like the Mercedes-Benz S-Class, Lincoln Aviator, and Audi A8. Oh, and remember the load-leveling air suspension properties our military developed for use in the second World War? Still relevant today. If youve ever seen or driven an unladen heavy-duty pickup, its obvious that the rear springs are built to support much more weight than just that of the bed itself. As a result, a conventionally sprung truck often exhibits an overly stiff rear end and can look as if its sticking its butt in the air, all because those springs are meant to compress under 2,000 pounds or so of payload in the bed. On the other side of the spectrum, its not uncommon to see an overladen pickup with its rear suspension sagging under all that weight. With a self-leveling air suspension (and adherence to gross-vehicle-weight ratings), those problems go away. Downsides? As you might imagine, theres a lot more tech involved in an air suspension setup than there is in a solid piece of metal or composite material. That means higher cost (for example, Volvo asks $1,800 to upgrade to air suspension in the XC90) and more parts susceptible to failure. And while overloading any spring can cause it to suddenly fail, metal or composite springs tend to sag as they age and fatigue while a worn or cracked rubber bellows can leak air and fail after a similar period of aging. The latter bit is especially important to consider on used vehicles, where failed air suspension can cost thousands to replace. Overload your Ram pickup and Rockauto.com will sell you a pair of new rear coil springs for about $100 each to get you back on the road. Meanwhile the dealer charges $431 per rear air spring, $1,275 for a compressor and $ 512 for the control module. Its one reason to think twice about buying any well-worn vehicle with air suspensionunless, of course, its recently had its airbags replaced or swapped for conventional springs. What do different automakers call their air suspensions? Airmatic (Mercedes-Benz) Air Glide Suspension (Lincoln) Smart Air Suspension (Tesla) Four-C Adaptive Air Suspension (Volvo) Adaptive Variable Suspension with Adjustable Height Control (Lexus) Active Air Suspension (Jaguar) Air suspension with Porsche Active Suspension Management (Porsche) Active-Level Four-Corner Air Suspension (Ram) Adaptive Air Suspension (Audi) The post Driving on a Cloud: How Do Air Suspensions Work? appeared first on MotorTrend .