My car has recently begun to feel rough. It has lost its smoothness during idling and more so when it accelerates. I can feel the roughness on the steering wheel and the floor when I am driving. Strangely, its performance appears to be unaffected and the engine is still responsive to the throttle. Fuel economy, too, remains the same. My car is six years old and has clocked 88,000km.
A car engine with a faulty fuel or ignition system will not run smoothly. Often, a defective gearbox can also cause roughness. Such problems with the powertrain will frequently manifest in performance and efficiency degradation.
If you are certain there is no loss in performance or fuel economy, the problem is likely due to inherent engine vibrations being transmitted to the body.
A car's engine and transmission - whether automatic or manual - are assembled rigidly together. When mounted on the car's chassis, the engine-gearbox assembly is isolated from the body by specially designed vibration absorbers.
These absorbers are often made of rubber or polyurethane, and sometimes liquid-filled for enhanced vibration damping. Without these absorbers - referred to as engine and gearbox mountings - vibration from either engine or transmission will be transmitted to the body.
These mountings wear with age. The rubber or synthetic material will harden and thus lose its vibration-absorbing property. Continuing to use a car with worn engine mountings will eventually cause other parts to deteriorate.
Have a workshop check the state of your car's engine mountings and change them if necessary. The replacement cost is not high.