You will need to declare this if you are going for an IVA. Depends on which company you use and what the HP company say. Some will allow it but others aren't so forgiving.
Sharing from experiences of dealing with debt
The greatness of a man is not in how much wealth he acquires, but in his integrity and his ability to affect those around him positively.
Bob Marley. http://kallis3.blogs.iva.co.uk
From the IVA point of view, if it is a reasonable (modest) vehicle, you will be allowed to keep it and the HP payments will be an allowable expense.
The issue is likely to be whether the finance company will let you keep it --- most have insolvency clauses in their terms, but not all of them act on such clauses. You would need to check with the finance company --- maybe an anonymous phone call.
My opinions are merely that .. opinions based on experience. Always seek professional advice.
IVA Completed 23rd July 2013 .... C.C. 10th January 2014 http://foggy.blogs.iva.co.uk