Yes it is a beautiful part of the World with some amazing driving roads. Worth using a bit of fuel for! The fact that there's very little traffic means you can usually drive as quick or as slow as you like and not hold anyone up!

Very beautiful! Going uphill I would think using highest gear and throttle up to 90% is the most efficient as long as you don't slow down too much and have to change gear. Then it is better to choose that gear from the beginning of the steeper slope if you can predict that.

Downhill depending on how steep it is at the moment i think alternating between coasting and engine braking in highest gear to restrict speed is best.

This is exactly what I do. I tend to get best MPG #'s when driving in mountainous areas.

Avoid downshifting unless absolutely necessary.

That's what I tend to do, but it seems to really drink the fuel. I guess there's no avoiding it. I find neutral is best as the engine braking slows you down too much, and you need to accelerate sooner, which uses more fuel than idling in neutral.

I guess it's not the same with all cars. Even with multiple climbs at near full throttle, I always see 40+ MPG at speeds of 55 MPH & under. 65-70 MPH in the mountains drops the numbers back to 40 if I maintain speed on the inclines.

It depends on the specifics of the hill and car. On my commute, I consider it good to get 20mpg while climbing the big hills when I had the HHR and Ranger. The Sonic does a little better. All being automatics limits my options, but the gen2 Prius could only manage 25mpg on the same incline.

Been practising a bit. It is a little upsetting seeing the trip MPG dash readout drop on every hill, on a hill I regulary climb, I see it drop from 47 MPG to around 42 MPG, but by the time I get home its avereaged out at around 50 MPG. I tend to stay in top gear and accelerate gently up the hill with as much throttle as the car needs. Theres a sweet spot in the throttle where the turbo provides enough power to pull up the hill at the speed limit, but as not to use much fuel.

Every cloud had a silver lining, although it uses fuel going up, the car uses almost no fuel going down so the incline/decline kind of counteract each other. I'm happy with 50 MPG, the official average for my car is 42 MPG so I should not complain!

There's no need to feel bad when the number drops as you climb the hill. Think of it as an investment. You're making energy as efficiently as you can and storing it in the car's mass, then you'll use the stored energy later when you would not be able to make it as efficiently.

Your car may be entering DFCO going down the hill, and actually using no fuel.

Well I do put the car in neutral going downhill. I appreciate the fuel cuts off if you leave it in gear, but I find the engine braking slows you down, and the need to accelerate again comes sooner in gear. But in neutral, yes it uses a bit to idle, but you can go 2 or 3 times further just on gravity. I've practised this technique and it works well.