Neil - the day will involve each car being put on the rolling road and it's power estimated using the "dyno" equipment. This will be done by personnel of Thorney Motorsport, not you. The car will be secured to the rolling road by straps, so there should be no "crashing". Just remember that we'll need an interpreter if you're gona bring any Essex boys along...
I assume that everyone will get a printout of how their car performed at the end of the day. The rest of the day is spent talking bollox about cars with your fellow members...
Graham - if your birthing plans allow, simply add your name to the list by copying & pasting from above and DavidT will bill you nearer the time. That's assuming we get the requisite numbers, of course.