I don't need to see any picture to believe him. I also did it!

If your girlfriend lives 350km away, drive there when there is no traffic (not 5pm Fridays), no passengers, light luggages, slow acceleration and concentrate on your cruising speed.
The biggest mpg killer is the speed, most people can't drive (without using the cruise) keeping a steady speed, they will floor the accelerator to pass, etc.

What i do:
Drive a steady speed without using the cruise, slowing down doing uphill and slowly accelerating back to you cruising speed. The cruise's goal is to keep a steady speed and will step on the gas to climb hills with a steady speed.
The A/C uses something like 0,5l/100km, turn that off.
Stay in gear while coasting, like slowing down from 80 to 40kph on 4th gear, the fuel injectors are completely off. In the other hand, clutch in (or putting the automatic in neutral) will burn some fuel while the engine is idling.
Wet roads increase tire rolling resistance (in my experience)
Cold air increase fuel consumption, we obviously know in Canada...

So, basically, drive alone, no ac, light music, focus on a steady speed of something like 95kph on the highway, and anybody would be able to do it.
Somebody did 3l/100km with a Ford Fusion Hybrid which is way over the expected fuel consumption, i don't remember where i read that...

 

Lucky my best was only 35mpg all highway cruising at 70 with up and down hills in a auto. commuting through work i get around 32 mpg at 70 with same terrain

 

700 km IS POSSIBLE.

I did 575 km. driving mostly in city.

The thing is: I drive very conservatively and I put the thing on "neutral" most of the time.

I am sure that someone on the highway at 70 km/h can do 700 km on a tank.

 

my best tank was 713 (near empty), mostly city driving. I do not know why it was so good that particular tank. Usually i get 600 km (when light comes on)

 

Wow....great MPG