ermes is targeting anyone who owns/drives a daihatsu cuore, and as a side show those who ride along as passengers. i'm sure you realise you have a unique ride (namely your daihatsu coure) and that he/she is something to celebrate.
i wish to encourage participation - there are no strict procedures. the honking of the horn mentioned earlier may not be ideal in some circumstances (or perhaps illegal), but where possible it may be useful/fun to attract the other daihatsu cuore's attention. it is very encouraged for you to celebrate in your own way.
this part is optional and not pertinent to being a member, but if you wish to say why you love your beast or share memories e.g. what he smelt like before he was yours, or his attraction to dirt - this is the place where at least one person will listen.