Strictly according to the rules: It is up to the competitor to class their car correctly ... or face a protest at the event. If no one protests, then the results stay. Brutal but technically correct.
I looked through the results and there appeared to be quite a few errors in classing and mostly likely to new people/new-to the-sport likely guessing at their class or perhaps not taking the time to figure out their class via reading the rules.....or perhaps not even knowing where to look in the first place? Dunno.
We did have a few threads on where people can look to class their vehicles.
Also, if people have no idea how to class their car, ask here on the forum. People can help if they are asked and there are plenty of knowledgeable people for that.
Some of this could maybe be caught at registration in the morning if there is someone savvy with classes present ... I had thought of printing out a list of classes etc. that we could have at the registration desk/table but a combo of lack of time and just plain forgetting to do so it did not happen. That might be the best option.