With a nice soft car cover like our Stormforce range, cats have also been known to use it as a scratch pad. Pawing at it because its "fun"!!
The solution is to use a Cat Deterrent, either a Catwatch or Catfree product, available from us here at Coveryourcar. The device is battery powered ( with mains option ) and sits in the ground pointing at your car. Once activated by a cat ( and only a cat ) it produces an Ultrasound for 10 seconds, unaudible to the human ear and scares away the cat. Over time the cat learns not to go near the protected area and hey presto, no more cat problem.
The Car Cover Specialists at Coveryourcar.co.uk