open container

[redsauced]

Does opening a bottle of wine, but not decanting still beneficial in the same way? Went to dinner last night across town with a 2000 Sestadisopra Brunello di Montalcino. I know this needs 3 hours decanted, but I don't know these folks well enough to show up at 5PM for an 8:00 sitting. So I opened the bottle at home, and then drove across town, over the Golden Gate Bridge with the wine open between my legs. Sorry! There was no other way to hold the bottle upright and drive at the same time.
So I arrived at the dinner, put the cork back in, and asked the hostess for a decanter. At dinner a little later the wine went splendidly with pasta and pork loin, but I felt the wine was too tight. So, how do I deal with this in the future? And sediment aside, is there a huge difference between open and decanted?

Sorry if this sounds like an episode of "Car Talk" on NPR. There is a reason why I'm posting in the novice forum.

[VouvrayHead]

There is a difference because in the bottle there's very little surface area for the wine to react with the air.
I'd try double decanting (pour wine into the decanter, then funnel back into bottle), during this process lots of air interacts with the wine...
Should help some vs. what you did, though probably not quite as much as if it was decanted good and proper.

[redsauced]

Ah yes, double-decanting. Seems obvious to me now. Thanks.

[Innkeeper]

Then, again it depends of the size of the mouth of the decanter. I've seen some that were no wider than the neck of a wine bottle. In these cases it makes no difference. That is why I always recommend wide mouth decanters.