Bit dated, but interesting: http://www.csparks.com/bmw/CarPriceVsIncome.xhtml

Thank you for that, certainly the most interesting is to see the most/least frugal car owners at the bottom of the page.

Seeing Lexus and Audi owners in the frugal list is kind of funny.

All the Lexus owners I know have emphasized the TCO rather than the luxury aspects to me. It's a nice car, but it's also a pretty reliable value.

Similarly, I've known some people who wished they had a Lexus, who I wouldn't call frugal.

I was hoping there would be an obvious answer. I guess I could rephrase the question this way: "is it common for people who make ~120k/year to drive a Porsche?" or "if you'd have a median income of all Porsche owners, what would it be?". I just want to get a general idea.

If you bought the Civic instead, and invested the difference, you'd be able to buy a lot more than a Porsche.

It's definitely not common. Partly because $120k doesn't go as far as you'd think if you live in a nice city, and partly because not everyone wants a Porsche. If you're into cars, and really wanted one, you could be driving a used 911 on that salary (if your other bills/expenses are reasonable, and you go with a tame model.) The thing to remember about expensive cars though, is the high cost of ownership. Insurance will cost more; Parts will cost more; Repairs will cost more; Tires and gas will cost more...

Is it common? No. Is it possible? Yes.