Steve, I could say my car was the car as seen on Wheeler Dealers, which is completely true - it shows up towards the end next to a load of other cars - but I'd be implying that it was "THE" car, which it isn't. That is all that anyone has had a problem with, including, it seems, your customers - the fact that your wording implies that.
Such as, for example, in this email to a potential customer:
"Hi i own the actual back ot the future delorean time machine used by universal studios, it arrives in the country tomorrow, the car is based in dover i could possibly help but it would be in the region of £1000 due to the transportation costs, if you want a bttf car there is no better car in Europe, please check out the site thanks steven"

Perhaps this video might also explain some of the problems people may have with you too:
http://www.theboltonnews.co.uk/news/..._for_the_day_/
see the titles at 0:40, and then the section from about 2:38

And of course this isn't the only example of you running down fellow owners' cars.