Pro Audio P.A. Car or Van Contest in UK?

I have had this urge for the longest time to set up an agency for the really loudest cars and vans in the UK. The sort you can hear coming for miles and can genuinely be used as public address. The Iceman, Edd Elson and A slew of Hertz demo cars, especially those from Source Sounds in Sheffield.
I had a few words about it with my chum the World’s Loudest Sound Engineer (Metallica and Led Zeppelin if they ever play again) and he thinks it’d be a hoot and as the world’s most experienced stadium sound engineer, he is well qualified to judge the cars (or vans’) output as to its viability as a public address- i.e. can you play music through it to act as the P.A. for an actual concert- gig live performance?
We have a bit of it going on over here, but just LOOK at these amazing installs from Latin American competitions. I think we aughta run one of our own and set the whole gamut of entrants up on a site to rent out their services as dance music providers for Public Appearances (the other sort of P.A.) at clubs and even in street events and gosh knows where else.

Here is a gallery of the insane vehicles I have been itching to hear – And FEEL – and as seen on Michael Palin’s BRAZIL recently, all parked on the beach, booming and nobody minds. In fact they love it. And in this hot outdoors-mostly land, it makes better sense. But just check THESE out!
link
The rules would be simple.
There are no rules – we just measure you from different distances using the Audio Control SA 3055 RTA and SPL meter!
The only ‘requirements’ would be that any vehicle can be connected to the mains via a big power supply and a fork-lift truck connector to be provided to connect indoors, whether or NOT they had the big 12V power supply and also that they have a well installed input and output set of RCA sockets…somewhere.
Whaddaya reckon? Should we do it and who would enter?