You need to do some serious homework on this as you will get yourself into big trubble

If you have a traders policy you ( in the eyes of the tax man ) openly admitting you trade , why else would you have a TRADE policy

People will come on here and say ,im not a trader and have a trade policy , but the tax man ( if he suspects you ) will use this against you

If a private man sells a car and it blows up on the way home he DOES have rights to get his money back , its a myth that private sale to private sale is risk free

If you buy and sell but try and keep out of the eyes of the tax man then your stupid , they WILL catch you , it may be a month it may be 2 years but they will get you

If you are a part time trader and sell a car that blows up on the way home and you refuse to sort it the buyer will grass you to the tax man anyway , lol

Also Chip
A legit trader can sell a car without warranty, its what you put on the reciept that matters

You are far better of contacting a good accountant and doing it legit , The accountant will keep your tax bill down anyway ( if there any good ) and then you can sleep at night