Are you Coke or Pepsi? PC or Mac? Hyundai, Honda, or Hummer? Heinz or Hunts?

Ever sneak a look at the person driving a car like yours to see what they looked like? Is the person younger, older, better-looking, thinner? We ask ourselves and note it down in our mental memory banks.

It’s superficial. Petty, maybe. And harmlessly fun. But it speaks to a deeper element of brand behavior as well. Because even for the trivial stuff, you may still make a judgment: She’s like me. She isn’t like me. Have you ever said you liked a brand just to get in the good graces of somebody?

Not only are brands a measure of how we define ourselves, they are a measure of how we define others. And our own relationship to a specific brand is what makes the difference. I may not have mentioned this for fifteen minutes or so, but brand power boils down to self-esteem. In other words, how a brand makes us feel about ourselves determines its strength and success. So peanut butter can make you feel like a better mother (because Choosy moms choose Jif), or a premium-priced overnight delivery service can make you feel like a smart manager.

But the self-esteem component is also given context by the group of people that a brand defines. A few years ago, Seth Godin wrote a book entitled Tribes, where he likened brand loyalty to tribal behavior. Another author, Douglas Atkins, wrote The Culting of Brands, about brands that create maniacal followers who help build sales as wild-eyed ambassadors for the product. Both authors have identified an intriguing part of the brand process, which is that we often see ourselves as part of a group that favors a certain brand concept over others.

For the most part this is a positive exercise, not a negative one. We don’t think a lot less of someone who isn’t in the group that drives the same car, wears the same clothes or roots for the same football team. But we do tend to like someone a bit more who is in our group. It creates commonality and connection. In some cases it can do much more.

Exhibit A: Saturn brand vehicles. As a car brand it lasted 25 years beginning in 1985, which is a relatively short run for the category. But from the start it created an exceptional brand loyalty among its owners, and hit a new gear with the first Saturn Homecoming event in 1988 where owners were invited to the manufacturing plant in Spring Hill, Tennessee to meet each other, retailers, plant employees and their families. Saturn created a sense of belonging that transcended the experience of driving the car itself. By the early 1990s, Saturn was high on the ownership satisfaction scale, trailing only several luxury brands. Saturn owners developed an unusually strong sense of group/tribe/cult. And for some years, Saturn was a successful brand that inspired other companies to imitate their approach.

Yet now it’s dead.

And the demise of the brand is the cautionary side of developing a following that’s too much about the tribe or cult and not enough about the experience of the product or service itself. At the risk of enraging the few remaining members of the Saturn Tribe, I’m going to go on record as saying that Saturn vehicles were essentially ordinary cars of the same quality as most other GM products. Which is not to say they were terrible, but they weren’t exceptional, either. Saturn’s biggest functional difference was their dent-resistant fiberglass body panels. Their biggest experiential difference was the friendly dealer concept based on no-haggle pricing, which eliminated one of most loathsome parts of the car buying experience.

Saturn was, in a sense, a social media brand before there was social media. Imagine the buzz it could generate now. Or could it? Because, ultimately, Saturn lost its brand following the same way it got it, by word of mouth. Loyal Saturn owners stopped buying them. They stopped telling their friends about them. They gave up their ambassadorships. And they found that Hyundais, Hondas and maybe some other GM cars were pretty decent transportation as well. And now they are likely loyal to them instead.

So the power of belonging can be highly effective for a brand, but it is also tenuous as well. Put another way, clicking the “Like” icon doesn’t really make you much of a tribe member. Repeatedly buying the product to the exclusion of all others and telling other people about it does. And that happens over time, not overnight.