FWIW, the rule about foglights turning off when the highbeams come on
is a DOT regulation that some states (but not all) enforce if/when
they do a safety inspection.

However stating it that way isn't exactly the rule. The rule is that
no more than 4 individual adjustable lights may be on simultaneously.
That means if your highbeams and lowbeams are part of one intergrated
headlight, it is legitimate to have your foglights on with them. If
(as several of my vehicles, including all my Vanagons) your highbeams
have a separate adjustable lamp from the lowbeam then when the high
beams come on the foglights have to turn off.

As I said, I got the real info through a round about source, but it
 >IS< a DOT regulation, which isn't heavily enforced. For instance
Lotus regularly ignored it, but the US DOT let the cars get sold anyway.

And yes, Virginia Safety Inspectors enforce the rule (damn it!)