Not sure if that would be useful, as there's no way to confirm whether a vehicle that was designed for leaded fuel was converted for unleaded, or if it simply runs on non-leaded additives.

Either way, there is this website, which used to really push for leaded petrol, it disappeared in 2009, but it almost reads like comedy:

http://web.archive.org/web/20090101030343/http://www.leadedp...

" Don't forget, if your local filling station doesn't sell leaded petrol, ask them to start!"

"Bayford is campaigning to have the extra duty on Leaded Petrol removed. You can help by printing this letter and sending it to your Member of Parliament"