One man company - car lease options

Buy a classic car, gut it and kit it out with a new engine and state of the art equipment. BIKitty BIK.

Do any of you know by any chance what is the max tax that can be claimed for a non-commercial car lease for a T/A (non VAt registered)? is it 20% over five years with a cap of 23K or should the full yearly amount paid claimed for?
And should this be entered as "133. Motor expenses.." or something else..? THX advance for any reponse! ;-)