I don't know how much "culture" you're going to pry from a bunch of gear heads. Here's some of mine; T-shirt, jeans, Oberon, barbecue, heavy metal, football, hockey, porn. That about sums it up.
Still, not a bad idea though. I too was kicking the idea around of starting a G-Machine based magazine and I even bought some books on how to start up a rag a few years ago. My thoughts were to make it more like Maxim magazine where the articles were more subjective and...yeah...it would touch on some other stuff like music, movies, gadgets, etc. You know...make the magazine look and feel different than the traditional car magazines. Up until about a couple of years ago, you could have swapped the covers of Chevy High Performance, Super Chevy, Car Craft, Hot Rod, and a few others and not been able to tell the difference. I think Hot Rod has changed that though. Their magazine does have a different look to it, and PHR has definitely upped the quality of their photography.
I will say this though...for it to succeed it has GOT to be about the car features. Less tech...more cars. Today, people buy car magazines for the cars. They get their tech (all the tech they're ever going to need, in fact) from the world wide web.
My $.02 anyway.