if you smelt it the 2 nd time you drove it and not until you turned on the air con, what makes you think the Dr even knew about it himself?
You have no come back on a private seller
http://www.moneysavin...refunds-exchange#must
"The rules change with private sellers
If you're buying second-hand goods from private seller (someone who doesn't sell goods for all or part of their living) your rights are nowhere near as strong as when buying from a shop.
The only protection is that it's correctly described and the owner has the right to sell it. Here it really is a case of caveat emptor or 'let the buyer beware'.
So if the seller says nowt or little about the goods and you buy it, then that's it. Even if it's shoddy, you weren't mis-sold, so have no comeback. Though if they lie to you – you do."
You prove they lied