If you looked into my car while we are on a day trip to see my Mom, you'd think I was one of those crazy people too. I have what looks like a Stanley, but is actually a knockoff that cost $10 Canadian, so about $7 U.S. It works just as well as the real thing - I fill it with water from home early in the morning, and it's still cold by the time we get home 12-15 hours later. Great for when we stop and eat our packed lunch along the way, and enough water for both Mr. SP and myself to share. The sharing/capacity aspects are why I bought it. I think there are a lot of knockoffs out there, so some people are at least being somewhat frugal about it. I do NOT lug this thing around while we are out and about though - I think that just looks ridiculous.