Group activities I don't understand

Here's a male activity that I don't understand: the collective cleaning of the car.

Every few months, My neighbor and his friends roll a baby shopvac out of his apartment, the cord trailing fifteen feet to his front door, and proceed to vacuum, dust and polish the car's interior. I've never seen them wash the outside of the car, presumably because there aren't any water hookups on the parkinglot side of the building. But the inside of this guy's car gets top at-home treatment.

Now in the nine years I've been driving my current vehicle, I think I've vacuumed it out twice. I probably have wiped down the dashboard a few more times, but that's mostly because when you transport cats over distance, they deposit fuzz, cage or no cage.

Would it be nice if the interior of my car was cleaner? Yes.

Do I feel the need to clean it? No.

I'd much rather exert cleaning effort on clothes, dishes, and hard to reach surfaces like the area behind my headboard which may be the cause of some of my nighttime stuffiness. Breathe Right strips, myass.

I understand that my cleanliness priorities don't line up with everyone else's. And I understand that there's just something about the bond between a dude and his car that invokes this sort of monthly activity. Yes, yes, grunting manly noises. Agreed.

Here's what I really don't get: all the dude's friends that help clean the car. 

Last week, there were four dudes out there cleaning. Willingly. It wasn't that they were being punished or that they wouldn't see their allowance if they didn't help. These were just four dudes, out there cleaning a sedan that last year sat in the same spot for four weeks with a flat tire. They didn't bring their own cars to clean, so it wasn't a "having a crew gets a big job done quicker" thing and it wasn't about being close to a super cool sports car -- although the rims on this thing could blind someone if the light hits them right. It was just an "I'm going to help my friend clean his car" thing. And I don't get it. I've volunteered my help to many friends many times -- sometimes even for cleaning -- but never have I helped a friend clean the inside of a car. Nor have I been asked to help. Sure, my parents made me when I was younger, but that's a wholly different power structure.