Basically i looked at autotrader or it could have been motors.co.uk , a few weeks ago where the ad was placed and was also able to go through to the car dealer site as well .
Is there anyway to see the advert for the car when it was up on the website ?
It takes snapshots of websites and stores them. If it didn't take a snapshot of the website you're interested in at the time you're interested in, then it won't be there.
Do you mean if a car that was on the website has been removed it's not possible to see the ad anymore - nothing has been recorded on my laptop anywhere?
If you haven't taken a snapshot of the page and web-site has changed the advert then no it'll no longer possible to view. You could go to the main page of the sites and do a search for the car... it still may have links to the dealer etc.