I can't recall ever having had such a Christmas party. Occasionally a close friend has insisted she bring a dish, but other than that, it's my cooking or nothing.
Bearing in mind it's summer here, we would often have BBQs and salads. Pretty easy to do.
But driving an hour with food on the floor of the car is a recipe for disaster, though I once transported a wedding cake from Canberra to Sydney, erecting the layers when I got to the venue. I know! Madness.
I have an easy Mexican dish that people rave about and is so easy to do.
Chilli con carne, layer of creamed corn, topped with lots of cheese. It's my take on pastel de choclo ,and everyone raves about it. Sooo easy to transport.
The actual recipe. below.
https://www.google.com/search?client=firefox-b-d&q=pastel+de+choclo
Have fun Susan.