Wendell -

You said "When asked what my heading will be I respond "My ground track will
be...". That seems to satisfy them.  I suspect thats what the controller
really wants so he/she can anticipate where your symbol will be crawling (or
in the case of Legacys, streaking) across the scope."

Actually a controller is not interested in the ground track that you intend
to fly. The pilot/controller glossary in the AIM says:

SAY HEADING - Used by ATC to request an aircraft heading. The pilot should
state the actual heading of the aircraft.

In the same vein when a controller asks you for your "airspeed" he/she is
asking for your indicated airspeed, that being what's indicated on the
airspeed indicator and NOT true airspeed.

Happy Motoring,

Ted Stanley