One particularly odd exception I've encountered: lots of older Buick models have the fuel door hidden under the rear license plate. The rear license plate on these models is mounted on a hinged bracket that folds down to expose the fuel port, which isn't obvious at all by appearance.

I found myself rather confused by this when I noticed at a glance that my grandmother's car didn't seem to have anywhere to put fuel in it.

My opel from 2004 doesn't have that triangle and fuel gauge is in center of cluster... Fuel cap is on right (passenger) side like in almost all opels.