I also have a Ford KA2, which is 13 years old and would probablt be worth less than £500 at the most. Would the OR still see this as an asset, taking into account its age and value? I don't need it for work but I do use it to visit my elderly mother at least once a week.
I'm afraid the chances are that if you do not require the vehicle for work purposes it will be claimed. I have seen cases where the value is half yours and it was claimed.