I tried mine in a Ford F-250 (a big, very American, pickup truck). It has an unswitched cigarette lighter socket that it definitely fit into correctly (there may have been a little gap, but less than the thickness of my fingernail), and it also has a switched "power outlet" socket, which it seemed like it fit into properly, but there was some raised molding around it, so it was a little hard to tell.
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Bitt Faulk