In the case of Hire Purchase agreements it's always advisable to speak to the creditor no matter what. The ymight turn around and say they're sending the boys round for the rings on your finger but on the other hand they might want to keep the money rolling on in as they're making more money from you paying each month than they would my selling the car at auction and then setting up a monthly repayment for the outstanding balance!
It also depends on how long you've had the car for. Most HP agreements will have clauses in them that say once you've paid "£X" they cannot reposses the vehicle without obtain permission from a court. There will also be a "£Y" value that states once you've paid this amount that you can hand the keys back, walk away and anything left over is there loss with absolutly zero come back on you! OK, it won't help you obtain credit from them in the future or any partner company they share info with but it won't go against you on your creditscore as you've met your contractural agreement and sometimes, it's the only way out and is better than defaulting on the agreement!
This little clause isn't advertised for numerous reasons that should be obvious but if you read you HP Agreement that you signed you'll find it there.
Mick
Oh, by the way... HELLO, i'm new around here!