No, sadly, you may not legally sell a car on HP (If that's what this is.) Under the Supply of Goods (Implied Terms) Sct 1973, you do not own the car until the final payment- the HP company retains ownership, not you or the garage that sold it to you. Follow up on Butterworth v Kingsway Motors if you'd like further understanding. If you sell, it is a breach of s.12 of the Sale of Goods Act 1979 as you have no right to sell the car which isnt legally yours. Thus, the buyer could claim all the money they paid to you back at any time- even if they have the car for 12 months. Hope this helps.