I change my EDC as often as I change my skivvies.... at least once every 24 hours.
In my car, at all times: 1) M7 bayonet in the trunk; 2) M7 bayonet on the floor behind the driver's seat.
-- I will add that I used to carry my SOG Tech I behind the driver's seat, but opted for some rotation so none of The Collection gets jealous.
When away from home there are no less than 4 knives carried in the vehicle. For example, this past weekend in the Mojave desert one would have found in the vehicle, in addition to the above two M7's: 3) SOG Nite Tech; 4) SOG Bowie.
It's a simple system, really, based on the fact that SOG's also enjoy going on vacation.
Cheers,
Carl