Boom! And the first hole is big enough to fit a car with no headlight leveling at all, neither automatic or manual.I'll offer up the headlamp levelling switch on the dash as being the way to tell. If your car has one, then you're on halogens. If it doesn't, then you're on xenons (with automatic levelling.)
Now to see if anyone can shoot holes in that theory :d
Absence of a jet wash system definitively indicate halogen lamps all right.P.S. I'd have thought that absence of a jetwash system should definitively indicate halogen lamps.
But it answers the OP's question :dBoom! And the first hole is big enough to fit a car with no headlight leveling at all, neither automatic or manual.
But yeah, if the car's been made this century, your theory does hold more water.