How do you build a community if google prevents users from finding it?

You go to the myriads of car communities and systematically promote your content for Nurburgring. It’s a niche site, and by the OP’s description we can safely assume that it’s quite usable since he’s been already approached by a sponsor. And since this is a site about a specific car circuit you just go to the actual place, or make an arrangement with the organizers to promote your site. Give a leaflet, or build an accompanying mobile app.

I'm not saying that circumventing Google is the easiest thing in the world, or the cheapest, but it's not mission impossible either. I didn't find Hacker News from Google, not the dozens of other tech communities I'm following.

Start local. With actual people. Advertise with posters on utility poles (oh well they do not exist anymore in most places so replace with a suitable alternative and go to your local church/mosque/dance club/whatever relevant). I'm not saying this will work, but it is how it used to work.

The existence of meatspace never stopped the early web from flourishing, so why should the existence of the modern web stop anybody from making a second web? The only reason that Google was useful is because it tapped into the trust network that already existed before it.

I feel like the social media churn has destroyed people's brains, because they're more interested in stopping people from doing things they don't like than doing something awesome themselves.

Before people knew the web was vast and required digging through. Now people think google is the web, so if it doesn't come up by the third search it might as well not exist.

You're not wrong, but this is also a great acid test. We need to work to help people understand google is most definitely not the internet, and where we fail or don't get through leave them behind. I don't know what comes next, but there's not room for everyone, and I include many here (and likely myself) in those who won't make the transition. We love to imagine people physically leaving Earth for Mars and beyond, but what follows the internet is going to happen far sooner.

That's exactly it, the people are different now. They don't have the same time or energy as before.

Same way people built a community before google?

it's not really a community if it relies on an influx of random strangers

facebook/twitter ads still works.

I know what you gonna say, but... ya... you knew.