What is the most direct/quickest driving route from North Conway, NH to Bar Harbor, ME in August?

The quickest and the most direct routes are different.

The quickest (4h15m driving only, no stops) can be found on Google maps.

It is not the straightest or most scenic.

We drove from Bar Harbor to St Johnsbury in May via Highway 2. It was a beautiful drive - some construction in a couple of places but all in all it was a good route. You could take Highway 2 to Gorham and go south to North Conway.

Checked it out on mapquest the routes are about the same in time and distance.

Bratsandbeer's route is the one I would take.

You get the slopes of Mt Washington and Bethel, ME, a very charming small town.

It isn't the fastest or most direct,though, but the differences are probably trivial.

Our daughter gets car sick; we are taking the "scenic route" through the Green Mountains and wanted to give her a bit of a break on our leg from NH into Maine.