There are a couple threads on here you can search for.In some communities it is identical to #2 diesel except for tax & dye.
it's actually impossible to grab a sample from the tank... it has a nice plastic mesh screen on it... (when i got into my accident i went to syphon out the FULL tank of fuel... didn't work too well...)they would NEVER pull over a car to do a 'random' check. unless they were suspicious, or received some kind of anonymous tip...