Demand my money back and if they say no, put it in the hands of a solicitor. I wouldnt muck about. They are clearly in the wrong and they know it.
First instinct, well yes - but I try not to huff and puff unless it's to my benefit.
While I'm 99% sure that they (at least the PX valuer at the other dealer) knew that the car was a stinker when they offered it to me, a prolonged argument over it would make things worse.
Because this isn't a new car, my rights to reject are slim. It'd all centre around what's 'reasonable' - if a certain degree of 'used car smell' was reasonable in a 18 month old, 20000m car).
The dealer would naturally insist that they get a reasonable chance to fix the smoke smell issue. Any solicitor would tell me that I must let them try.
Let's say they do valeting and the fogging 'bomb' thing that's supposed to fix the stale smoke smell (see for example
http://www.clean-image.co.uk/articles/odour-kill-eliminate-cigarette-smoke-smells-01.htm). Now, I pick up the car and it smells OK, but later (
after the 30 day No Quibble Exchange period is up), perhaps in Summer when it's hot, the smell returns. That'd be it ... from then on I'd be lumbered with it.
So right now, I'm hoping they're hungry - offering them more money to get a new/newer car. For me, I get a 0m or perhaps 100m car, a full warranty and an '09 plate (vs the current smokey '57, 20000m car). Maybe they're desperate to achieve a new sales target?
(All this'd be a lot easier if the Aygo wasn't so darned popular and if its residuals were lower! Citroen are negotiating on the C1, but Toyota hardly budge on the Aygo).