A car's rear suspension has an important impact on its operation. Independent rear suspensions are configurations that don't use a solid rear axle to connect the two rear wheels. Instead, each wheel can move up and down independent of the other wheel. This system has some advantages for auto designers and drivers along with certain drawbacks.
One of the biggest advantages of an independent rear suspension is improved ride quality. Since the wheels can each react to variations in the road surface, one wheel's upward motion over bumps (or downward motion into potholes) doesn't telegraph across the axle to the opposite wheel. Instead, each wheel is always at its own optimal position, reducing the effect of bumps and providing a smooth, even ride for passengers.
Independent rear suspensions offer both pros and cons in terms of performance. Cars equipped with an independent rear suspension will see poorer performance when driving in a straight line, because the rear drive wheels can come off the road surface individually, resulting in a loss of traction and driving power.
At the same time, an independent rear suspension gives a car better cornering ability since there is less unsprung weight (the weight of the wheels ans suspension system) to pull against the driver's steering.
An independent rear suspension is more expensive to produce and maintain than a solid rear axle. The system includes several moving parts, each of which needs to be designed and manufactured to exact specifications. Independent rear suspensions also add cost in terms of testing and a longer assembly process. More parts also mean more opportunities for mechanical failure, giving an independent rear suspension more chances of needing repair.
Independent rear suspensions became popular among custom hot rod designers just as they were appearing on factory sports car models. For these do-it-yourself car designers, an independent rear suspension was also a chance to give a vehicle a unique look. Even today, hot rods often include elaborate, chrome-plated rear suspensions that are easily visible to drivers behind the car, making a visual statement and showing the designer's attention to detail.